MOTOR  Tl    ::.:'.; 

UTOMOBiLEMOTORS 
••«»  MECHANISMc 


Mechanics  Department 


i&wt»viryitiry»i&«igifl^ 


MOTOR  TRUCK 

and 

AUTOMOBILE 

Motors  and  Mechanism 


A  Practical  Illustrated  Treatise  on 
the  Power  Plant  and  Motive  Parts 
of  the  Modern  Motor  Vehicle,  for 
Owners,  Operators  and  Repairmen. 


BY 

THOMAS  H.  RUSSELL,  A.M..M.E. 

with 

Numerous  Revisions  and  Extensions 

BY 
JOHN  B.  RATHBUN,  M.  E. 

' 


Consulting  Engineer  and  Instructor 


Chicago  Technical  College 


-8 

lillillllljllllllllliilllllllllliillllllllllllllll 

51  s 

I 

CHARLES  C.  THOMPSON  CO. 

|  CHICAGO,  U.  S.  A. 

1917  15 


'/1/7 


ary 


MECHANICS   DEPf. 
COPYRIGHT,  1917 

BY  CHARLES  C.  THOMPSON  CO. 
CHICAGO 


MOTOR  TRUCKS 

Copyright,  MCMIX 

THE  CHARLES  C.  THOMPSON  CO. 

[Not  Inc.] 

Copyright,  MCMXII 

By  CHARLES  C.  THOMPSON  CO. 

CHICAGO.  U.  S.  A. 


PREFACE 

The  purpose  of  this  book  is  to  present  in  a  clear,  concise 
manner  the  essential  facts  regarding  the  construction  and 
operation  of  the  modern  automobile  and  motor  truck.  In- 
cluded in  the  text  are  many  useful  hints  and  rules  for  locating 
and  repairing  the  many  ills  to  which  the  motor  vehicle  is  heir. 
Special  attention  has  been  paid  to  the  operation  and  repair  of 
the  Ford  chassis,  whether  used  as  a  pleasure  car  or  truck. 
This  makes  the  book  more  than  ordinarily  valuable  to  the 
owner  of  this  popular  little  car,  as  the  Ford  has  many  peculiar 
features  of  construction  not  used  on  other  automobiles. 

In  principle  of  construction  the  motor  truck  does  not  differ 
greatly  from  the  pleasure  car,  but  the  differences  in  detail  are 
fully  described  in  a  separate  chapter.  Electric  cars  and  trucks 
are  also  included. 

Beginning  with  a  simple  description  of  the  relation  between 
the  parts  of  an  assembled  car,"  the  reader  is  led  in  easy  and 
logical  steps  to  a  detailed  analysis  of  the  construction  of  the 
various  items,  their  maintenance  and  repair.  The  construction 
and  operation  of  the  gasoline  motor  receives  particular  atten- 
tion. Such  new  features  as  the  electric  gear  shaft,  vacuum 
fuel  feed,  and  the  eight-cylinder  motor  are  described  in  detail. 

Ignition  and  electric  self-starting  devices  found  on  every 
modern  machine  are  given  particular  attention  as  the  electrical 
equipment  is  generally  the  least  understood  feature  of  the  con- 
struction. A  comprehensive  illustration  of  the  electrical  circuits 
is  included  in  the  chapter  on  Self-Starting. 

735/71 


CONTENTS 

Chapter  •  Page 

I.  ESSENTIAL  PARTS  OF  A  MOTOR  CAR. . .       7 

The  Assembled  Car  —  Duties  of  the  Motor, 
Transmission,  Differential,  etc. 

II.  THE  INTERNAL  COMBUSTION  ENGINE.     19 

Principles  and  Construction — Cycle  of  Oper- 
ation— Cylinders,  Pistons,  Connecting  Rods, 
Crank-Shafts,  etc.  —  The  Eight  Cylinder 
Motor. 

III.  FUNCTION  OF  MOTOR  PARTS 35 

Detailed  Description  of  the  Various  Parts  of 
the  Gasoline  Motor,  and  Hints  to  Their  Proper 
Maintenance — The  Cooling  System. 

IV.  MOTOR  TRUCKS   44 

Difference  Between  Pleasure  Car  and  Motor 
Truck  —  Control  Systems  —  The  Electric 
Truck — Governors. 

V.  CLUTCHES 61 

Purpose  of  Clutch — Cone  Clutches — Wet  Disc 
Clutch— Dry  Disc  Clutch— Cutting  Clutch 
Leather. 

VI.  TRANSMISSION  OR  "CHANGE  GEAR". ...     71 

Selective  Sliding  Type  Transmission — Elec- 
tric Gear  Shift — Planetary  Transmission — 
Ford  Type  of  Planetary  Transmission. 

VII.  CARBURETERS  AND  FUEL  SUPPLY 85 

Purpose  of  Carbureter — Surface  and  Jet 
Types — Multiple  Jets — Modern  Carbureters — 
Filters — Stewart  Vacuum  Feed  System. 

4 


MOTORS  AND  MECHANISM 


CHAPTER  I. 
ESSENTIAL  PARTS  OF  A  MOTOR  CAR. 

We  may  classify  motor  vehicles  under  four  different  types : 

(1)  Those    propelled  by  means  of  internal    combustion 
engines. 

(2)  Those   propelled   by   steam    engines. 

(3)  Those  propelled  by  electric  motors  supplied  with  cur- 
rent from   a  storage  battery. 

(4)  Those  propelled  by  electric  motors,  using  current  gen- 
erated on  the  car  by  means  of  an  internal  combustion  engine. 

It  is  with  the  first  that  we  shall  have  mostly  to  deal,  for 
steam  and  electric  cars,  though  successful  in  operation  and 
having  many  firm  friends  and  advocates,  are  at  present  in  the 
minority. 

In  Figs,  i  and  2  we  show  how  the  arrangement  of  the 
various  parts  of  the  motor  car  is  carried  out. 

In  Fig.  i  we  have  a  chain-driven  car,  and  in  Fig.  2  a  gear- 
driven  car.  The  difference  between  the  two  is  small.  We 
will  take  first  a  chain-driven  car,  and  in  most  cases  we  have 
given  the  same  reference  letters  to  the  same  parts  in  Figs. 
i  and  2.  A  is  the  engine — in  this  case  a  four-cylindered  en- 
gine (it  may,  of  course,  be  of  one,  two,  three,  four,  six,  or 
eight  cylinders,  and  may  be  arranged  differently  as  regards 
the  inlet  and  exhaust  from  the  method  shown  in  our  diagram). 
B  is  the  flywheel  of  the  engine  and  this  may  be  regarded  as 
the  point  where  the  power  is  transmitted  from  the  engine 
to  do  the  work  of  propelling  the  car.  Inside  B  is  the  female 


8 


MOTORS  AND  MECHANISM 


portion  of  a  clutch,  the  male  portion  being  shown  at  C. 
This  clutch  is  for  the  purpose  of  connecting  or  disconnecting 
the  engine  to  or  from  the  transmission  mechanism '  which 
transmits  the  power  to  the  road  wheels.  D  is  a  shaft  which 
is  driven  by  the  male  member  C  of  the  clutch  when  it  is  in 
engagement  with  the  female  member  B.  It  is  kept  in  engage- 
ment by  means  of  a  spring  shown  diagrammatically  in  our 
illustration.  It  may  be  arranged  in  a  variety  of  ways,  de- 
scribed in  greater  detail  under  the  heading  Clutch. 


PIG.    i.-DIAGRAMMATIC   PLAN  OF  MOTOR  CAR  WITH  CHAIN 
TRANSMISSION. 

A,  Engine. 

B,  Fly-wheel  and  female  portion  of 

clutch. 

C,  Male  portion  of  clutch. 

D,  Transmission  shaft. 

E,  Change  speed  gear  box. 
.H,  H,  Countershaft 

J,  J,  Front  chain  sprockets. 

J,  J,  Back  chain  rings. 

1C,  Driving  chain. 

L,L,  Fixed  axle. 

M,  M,  Back  road  wheels. 


N,  Accelerator  pedal. 

O,  Brake  pedal. 

P,  Clutch  pedal. 

Q,  Clutch  spring. 

R,  Brake    and  change  sjeed  lever 

quadrant. 
S,  Starting  handle. 
U,  Carbureter. 
W,  Engine  or  crank  shaft. 
Y,  Radiator. 
Z,  Exhaust  Mujfte* 


The  internal  combustion  engine  being  incapable  of  starting 
until  the  crank  shaft  has  been  revolved,  there  is  a  starting 
handle  S  in  front  of  the  car  which  is  put  into  communication 
with  the  crank  shaft,  but  which  automatically  comes  out  of 
engagement  as  soon  as  the  engine  is  started. 

Y  is  the  radiator,  placed  in  front  of  the  engine;  some- 
times it  has  a  fan  behind  it,  at  other  times  the  flywheel  of 
the  engine  forms  a  fan,  the  object  being  to  accelerate  the 
speed  at  which  the  air  is  drawn  through  the  radiator  for 
cooling  purposes.  U  represents  the  position  of  the  carbure- 
ter on  the  inlet  side  of  the  engine.  The  carbureter,  of  course, 


MOTORS  AND  MECHANISM  9 

may  be  placed  at  either  side  of  the  engine,  and  sometimes, 
where  the  inlet  and  exhaust  valves  are  all  on  one  side,  it  is 
placed  on  the  other  side  on  a  pipe  which  leads  through  be- 
tween the  two  pairs  of  cylinders  to  supply  them  with  gas. 
W  is  the  crank  shaft,  to  which  the  flywheel  B  is  rigidly 
secured. 

The  parts  which  we  have  described  represent  the  power- 
generating  plant.  We  will  now  describe  that  portion  which 
is  purely  for  transmission  purposes.  D  is  a  shaft  coupled 
to  the  male  portion  of  the  clutch  C.  This  shaft  is  only 
rotated  by  the  engine  when  the  clutch  is  in  engagement. 
It  then  drives  through  into  the  gear  box  E.  In  the  gear 
box  is  provided  a  change  speed  gear  mechanism  (see  Change 
Speed  Gear),  and  also  the  differential  gear  and  the  bevel 
wheel,  by  means  of  which  the  power  is  transmitted  from  the 
longitudinal  shaft  in  the  gear  box  to  the  cross  shafts  H,  H, 
known  collectively  as  the  countershaft,  which  is  arranged 
transversely  in  the  frame.  The  ends  of  these  shafts  carry 
sprocket  wheels  J,  J,  these  sprocket  wheels  being  connected 
by  means  of  the  chains  K  to  larger  sized  sprocket  wheels 
attached  to  the  hubs  of  the  rear  wheels.  These  sprocket 
wheels  are  marked  Ji,  J.  L,  L  is  a  solid  forged  axle  carry- 
ing at  its  ends  the  road  wheels  M,  M,  which  revolve  about  it. 

Z  is  the  muffler,  into  which  the  exhaust  gases  from  the 
engine  flow. 

There  are  three  pedals  shown  just  over  the  clutch.  P  is 
the  clutch  pedal,  by  depressing  which  the  clutch  is  taken 
out  of  engagement.  O  is  a  pedal  which  operates  a  brake, 
generally  on  the  countershaft.  N  is  the  accelerator  pedal 
used  to  hold  up  the  governor,  and  to  thus  allow  the  engine 
to  attain  its  highest  speed. 

The  method  of  arranging  a  motor  car  as  we  have  described 
is  one  of  the  earliest,  and  is  still  used  in  a  very  great  num- 
ber of  up-to-date  and  high-powered  cars.  The  chain  trans- 
mission, however,  although  it  has  many  advantages,  is  often 
noisy,  and  in  the  more  modern  cars  using  this  type  of  trans- 
mission chain  cases  have  been  fitted  not  only  to  deaden  the 


10 


MOTORS  AND  MECHANISM 


noise,  but  also  to  protect  the  chain  from  dirt  and  to  insure 
its  proper  lubrication. 

In  Fig.  2  we  show  in  diagrammatic  form  a  representative 
arrangement  of  a  car  in  which  the  transmission  is  by  gear- 
ing instead  of  chains,  and  cars  using  this  method  are  known 
as  gear-driven  cars. 

So  far  as  the  engine,  the'  clutch,  and  the  shaft  D  go,  this 
arrangement  is  practically  the  same  as  that  in  a  chain- 
driven  car,  but  the  gear  box  is  so  arranged  that  there  is  no 


JFIG.  a.— DIAGRAMMATIC  JPLAN 
OR  GEARED 

A,  Engine. 

B,  Fly-wheel  and  female  portion  of 

clutch. 

C,  Male  portion  of  clutch. 

D,  Transmission  shaft. 

E,  Change  speed  gear  box. 

F,  Differential. 

G,  G,  Live  axle. 

N,  Accelerator  pedal. 
O,  Brake  pedal. 
P,  Clutqh  pedal. 


OF  MOTOR  CAR  WITH  LIVE  AXLE 
TRANSMISSION. 

Q,  Clutch   spring. 

R,  Brake,  and  change  speed  lever 
quadrant. 

S,  Starting  handle. 

T,  Cardan  or  propeller  shaft 

Ti,  T2,  Universal  joints. 

U,  Carbureter.' 

W,  Engine  or  crank  shaft/ 

Y,  Radiator. 

Z.  Exhaust  JtfufVW, 


transverse  shaft  in  it,  and  it  does  not  contain  the  differential 
gear.  Instead,  it  transmits  the  power  directly  either  from  the 
primary  or  the  secondary  shaft  (see  Change  Speed  Gear)  to 
a  differential  gear  which  is  incorporated  inside  tne  case  which 
forms  the  rear  axle.  As  the  gear  box  E  is  attached  directly 
to  the  frame  of  the  car,  and  as  the  axle  which  carries  the  road 
wheels  M  is  attached  to  the  car  through  the  medium  of 
springs,  the  relative  position  of  the  rear  axle  and  gear  box 
would  be  constantly  altered,  owing  to  road  inequalities.  In 
order,  therefore,  to  transmit  the  power  from  the  gear  box  E 
to  the  differential  gear  inclosed  in  the  case  F,  some  form  of 


MOTORS  AND  MECHANISM  11 

shaft  must  be  used  which  will  allow  of  movement  up  and 
down  and  sideways,  the  up  and  down  movement  being 
the  most  pronounced.  This  shaft  is  shown  at  T,  and  is  known 
as  the  propeller  shaft.  It  has  a  universal  joint  Ti  at  its 
forward  end,  so  that  the  rise  and  fall  of  the  back 
axle  relatively  to  the  frame  will  not  affect  the  transmis- 
sion of  .the  power.  In  some  cases  the  propeller  shaft  has 
a  universal  joint  at  either  end,  as  in  our  illustration,  and  can 
then  be  described  as  a  cardan  shaft.  The  rise  and  fall,  in  the 
case  of  the  arrangement  shown  as  at  Fig.  I,  where  chains  are 
used  to  transmit  the  power,  is  allowed  for  by  the  chains  them- 
selves. 

The  power,  being  transmitted  to  the  bevel  wheel  inside  the 
differential  case  F,  is  transmitted  from  the  differential  gear 
to  the  road  wheels  by  means  of  shafts  shown  in  dotted  lines 
at  G.  These  shafts  run  inside  the  hollow  axle  shown,  and,  at 
their  ends,  are  anchored  to  the  wheels  M,  M. 

Change  Gears  or  Transmission. 

Unlike  the  steam  engine,  the  gasolene  motor  does  not  pull 
well  at  low  rotative  speeds,  and  for  effective  work  must  not 
be  allowed  to  drop  below  a  certain  limit  whether  the  car  is 
traveling  fast  or  slow.  To  obtain  a  fair  engine  speed  with  a 
resulting  heavy  pull  at  the  road  wheels,  it  is  necessary  to 
change  the  relation  between  the  revolutions  of  the  engine 
and  road  wheels.  This  is  done  by  either  gears  or  some  equiva- 
lent device,  so  arranged  that  the  ratios  can  be  temporarily 
changed. 

There  are  several  ways  in  which  the  gears  can  be  arranged, 
the  principal  systems  being  the  "planetary"  and  the  "sliding" 
types.  Both  systems,  however,  have  in  common  the  ability 
to  increase  the  leverage  of  the  engine  over  the  road  wheels, 
and  to  allow  the  engine  to  run  faster  or  slower  in  regard  to  the 
wheels.  By  shifting  a  set  of  gears  a  small  gear  on  an  extension 
of  the  engine  shaft  is  brought  into  active  mesh  with  a  larger 
gear  on  the  driving  shaft,  thus  allowing  the  engine  to  run 
faster.  When  the  next  higher  speed  is  desired,  the  first  gears 


12 


MOTORS  AND  MECHANISM 


I ,  I 
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W   *o   .c/2  |g 

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Q  4..«. 

B 

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W    J^j 

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MOTORS  AND  MECHANISM  13 

are  shifted  out  of  mesh  and  a  second  pair  are  mated  which 
gives  a  smaller  ratio.  In  normal  running  all  gears  are  shifted 
out  of  mesh  and  the  engine  is  directly  connected  with  the  road 
wheel  driving  shaft  by  means  of  a  jaw  clutch  so  that  the 
driving  shaft  runs  at  engine  speed.  For  the  forward  speeds 
there  may  be  from  one  to  three  gear  changes,  according  to 
the  size  of  the  car.  The  Ford  has  one  geared  and  one  direct 
speed.  The  heavier  cars  generally  have  two  geared  speeds 
and  one  direct  speed. 

As  the  gasolene  engine  cannot  be  reversed,  there  is  a  second 
gear  combination  that  reverses  the  rotation  direction  between 
the  engine  and  the  propeller  shaft. 

A  number  of  devices  have  been  placed  on  the  market  in- 
tended to  supplant  the  gear  system.  All  of  these  provide 
a  far  greater  number  of  speeds  than  would  be  possible  with 
gears,  but  all  of  them  have  developed  more  serious  faults  than 
the  old  gear  system. 

Example  of  Modern  Chassis. 

The  accompanying  cut  is  an  example  of  a  modern  6  cylinder 
shaft  driven  chassis  shown  in  plain  view.  From  the  descrip- 
tion already  given  the  relation  of  the  parts  can  be  readily 
traced.  The  six  cylinder  motor  at  the  right  has  the  cylinders 
cast  in  pairs,  that  is  in  groups  of  two  as  indicated  by  A-A-A, 
each  letter  being  placed  on  a  unit  of  two  cylinders.  The 
clutch  C  is  mounted  in  the  fly-wheel  J,  the  stub  end  of  the 
shaft  running  into  the  transmission  or  change  gear  box  B. 
From  the  gear  box  B  the  propeller  shaft  P  runs  into  the 
differential  casing  D  on  the  rear  axle.  The  gears  in  the 
casing  are  shifted  by  the  lever  G  on  the  center  of  the  gear  box. 
K  and  K1  are  the  running  boards,  and  W-W1-W11-W111  are 
the  road  wheels.  The  steering  wheel  is  indicated  by  H.  Gaso- 
lene is  stored  in  the  tank  F  at  the  left,  from  which  it  is  forced 
to  the  carbureter  by  air  pressure.  The  exhaust  gases  from  the 
engine  pass  through  the  exhaust  pipe  E  to  the  muffler  I.  From 
I,  the  gases  pass  through  U  to  the  atmosphere.  Two  universal 
joints,  O  and  O1,  are  placed  at  either  end  of  the  propeller  shaft 


i4  MOTORS  AND  MECHANISM 

P  so  that  the  action  of  the  springs  when  passing  over  rough 
roads  will  not  interfere  with  the  rotation  of  shaft.  From  D 
the  power  is  transmitted  through  a  bevel  gear  to  the  two  rear 
road  wheels  W11  and  W111. 

At  the  center  and  inside  of  the  rear  wheels  are  the  brake 
drums  M  and  M1.  A  brake  shaft  N  is  provided  with  small 
levers  (at  upper  end)  which  are  known  as  "equalizers."  These 
levers  allow  the  pressure  of  the  brake  pedal  1,  or  the  emer- 
gency brake  lever  G2,  to  be  transmitted  to  both  the  drums  of 
the  left  and  right  road  wheels  with  equal  force.  If  the  force 
on  the  drums  were  not  equal,  there  would  be  excessive  wear 
on  the  tires. 

Unit  Power  Plant. 

In  the  larger  types  the  engine  and  transmission  are  arranged 
as  two  independent  units.  Both  units  in  this  construction  are 
attached  to  the  main  frame  through  cross-members  or  by  long 
arms.  Due  to  the  flexing  of  the  chassis  frame  in  passing  over 
rough  ground  there  is  a  continual  change  in  the  alignment 
of  the  engine  and  transmission  shafts,  making  it  necessary  to 
place  some  form  of  flexible  joint  between  the  two  units. 

In  practically  all  medium  weight  and  light  cars  it  is  the 
practice  to  have  the  engine  and  transmission  combined  in  one 
unit  so  that  no  flexible  couplings  are  necessary.  This  reduces 
both  the  weight  and  number  of  parts,  cuts  down  the  fuel  and 
maintenance  expense  and  in  addition  makes  the  power  plant 
shorter.  A  power  plant'  in  which  the  motor  and  transmission 
are  combined  as  one  part  is  known  as  a  "Unit  Power  Plant." 

Three  Point  Suspension. 

When  a  motor  or  transmission  is  suspended  from  the  frame 
so  that  it  is  bolted  to  the  frame  at  four  points,  every  deflection 
or  twist  in  the  frame  is  transmitted  to  the  engine  or  transmis- 
sion, causing  the  shaft  to  spring  and  the  bearings  to  bind. 


MOTORS  AND  MECHANISM 


To  avoid  this  trouble,  both  the  engine  and  the  gear  case  are 
suspended  at  three  points  on  the  frame,  the  joints  being  rather 
flexible.  Two  points  are  attached  to  the  outside  members, 
while  the  third  point  is  attached  to  the  center  of  a  cross  mem- 
ber so  that  when  the  frame  is  sprung  the  engine  will  rotate 
slightly  about  the  central  third  point.  This  rotation  will,  of 
course,  prevent  strains  from  being  thrown  into  the  engine  or 
transmission. 

The  unit  power  plant  is  an  ideal  arrangement  for  the  appli- 
cation of  the  three  point  principle  as  the  arms  are  short  and 
only  one-half  of  the  attachment  points  are  needed  when  com- 
pared to  the  two  unit  system. 

A  four  cylinder  car  is  illustrated,  the  cylinders  being  cast  in 
two  blocks,  A-A1,  two  cylinders  per  block.  The  engine  crank- 


FOUR  CYLINDER  UNIT  POWER  PLANT. 

The  Engine  Crank-Case  E,  the  Transmission  F,  and  the  Fly-Wheel  Housing  Bare  in 
One  Unit  Supported  at  the  Points  O,  C,  C'. 

case  E  is  cast  in  one  part  with  the  fly-wheel  housing  B,  the 
fly-wheel  being  entirely  enclosed  with  access  through  the 
removable  cover  D.  The  transmission  casing  F  is  bolted  to 
the  fly-wheel  casing  at  Y,  making  the  engine  and  gear  casing 
a  single  unit.  Two  short  arms  C  and  C1  attach  the  unit  to  the 
frame  L-L1,  and  as  these  are  part  of  the  large  diameter  fly- 
wheel housing  they  are  comparatively  short.  The  third  point 
of  suspension  is  at  O  on  the  frame  cross  member  N".  It  is 
about  O  that  the  plant  oscillates  with  the  springing  of  the 
frame.  The  radiator  R  is  often  mounted  on  member  N  in 


16  MOTORS  AND  MECHANISM 

such  a  way  that  stresses  from  the  frame  are  not  thrown  into 
the  delicate  core  of  the  radiator. 

The  differential  housing  J  on  the  rear  axle  tube  T  is  con- 
nected with  the  transmission  F  by  the  propeller  shaft  Z,  either 
one  or  two  universal  joints  being  attached  at  H  or  I.  To 
prevent  the  rear  axle  from  turning  in  a  direction  opposite  to 
the  rotation  of  the  wheels  because  of  the  twist  of  the  motor,  a 
torque  tube  K  is  fastened  rigidly  to  the  differential  and  is 
pivoted  on  the  transmission  or  cross-member  at  X.  With 
some  machines,  the  torque  tube  is  omitted,  the  springs  being 
designed  so  that  they  will  take  the  torque  to  the  motor.  This 
is  known  as  the  "Hotchkiss  drive."  The  springs  are  indicated 
by  p-pi-pii-pm  and  the  wheels  by  S-S-S-S.  The  gear  shift 
lever  and  segment  is  at  M,  with  the  brake  drums  at  W-W. 
Muffler  at  U,  exhaust  pipe  Q. 

When  laboring  up  a  hill  the  twisting  action  of  the  rear 
axles  is  surprisingly  great,  and  if  the  springs  are  to  be  used 
alone  with  the  exclusion  of  the  torque  tube  they  must  be 
substantially  constructed.  One  thing  in  favor  of  receiving  the 
torque  through  the  springs  is  that  fact  that  the  flexing  of  the 
springs  reduces  the  jar  on  the  engine  and  transmission  when 
starting  suddenly  or  when  striking  obstacles  in  the  road. 

The  Differential  Gear. 

In  turning  a  corner  the  outside  wheels  revolve  more  rapidly 
than  the  inside.  If  both  wheels  were  mounted  on  either  end 
of  a  rigid  axle  one  wheel  would  have  to  slip  to  make  up  the 
difference  in  speed. 

To  prevent  this  trouble  the  rear  axle  in  shaft  driven  cars  is 
split  with  the  inner  ends  connected  through  a  system  of  gears, 
and  the  drive  from  the  motor  is  applied  to  them  in  such  a  way 
that  an  equal  amount  of  power*  is  transmitted  to  each  wheel. 
In  thexase  of  the  chain-driven  car  the  rear  axle  is  left  solid 
with  the  wheels  revolving  on  the  axle.  The  difference  in  the 
wheel'speed  is  taken  up  by  splitting  the  counter-shaft,  and  apply- 
ing the  differential  gear  at -this  point.  The  differential  gear  for 
this  car  is  placed  in  the  gear  box. 


MOTORS  AND  MECHANISM  17 

With  shaft  drive,  the  end  of  the  propeller  shaft  Z  at  J 
carries  a  bevel  pinion  that  meshes  with  a  larger  bevel  gear  on 
the  axle  T.  At  this  point  the  motor  speed  is  reduced  to  the 
speed  of  the  road  wheels. 

Radius  Rods  and  Torque  Tubes. 

Owing  to  the  fact  that  the  axle  tends  to  turn  in  a  direction 
opposite  to  that  of  the  wheels  on  either  chain  drive  or  shaft 
driven  cars,  it  is  necessary  to~prevent  this  twisting  by  either 
increasing  the  strength  of  the  springs  or  by  running  a  rod  from 
the  axle  to  the  frame.  In  addition  to  the  "torque"  or  twist, 
the  pull  of  the  chains  on  a  chain  driven  car  tends  to  pull  the 
axle  back  and  forth  so  that  rod  braces  must  be  used  to  keep 
the*  distances  constant  between  the  transmission  sprocket  and 
the  sprocket  on  the  rear  wheels.  If  this  is  not  done,  the  vary- 
ing distances  will  alternately  tighten  and  slacken  the  chains. 

When  the  car  is  of  the  shaft  driven  type,  and  only  the  twist 
is  to  be  taken  care  of,  a  rigid  rod  K  is  run  from  the  differential 
case  J  to  the  cross-member,  the  rod  being  joined  to  the  frame 
cross-member.  With  a  chain  driven  car,  two  rods  run  from 
each  end  of  the  axle  to  the  frame,  the  frame  ends  of  the  rods 
being  pivoted  to  the  ends  of  the  driving  sprocket  tubes.  At  the 
latter  point  they  are  provided  with  adjustments  so  that  the  chain 
can  be  kept  at  the  proper  tension.  This  is  necessary  as  the  chains 
stretch  in  service. 


i8 


MOTORS  AND  MECHANISM 


MOTORS  AND  MECHANISM 


CHAPTER  II. 
THE  INTERNAL  COMBUSTION  ENGINE. 

Internal  Combustion  Engine — This  is  the  term  which  per- 
haps best  describes  the  gasolene  engine  or  motor  with  which 
most  automobilists  have  to  do.  The  principle  of  operation 
is  based  on  the  well-known  facts  that  gasolene  vapor  or  a  fine 
spray  of  gasolene  mixed  with  air  forms  a  highly  inflammable 
mixture,  and  that  if  this  mixture  be  confined  in  a  closed  cham- 
ber and  ignited  by  a  flame  or  spark  it  will  explode  and  expand. 
This  is  just  what  is  done  in  a  gasolene  engine,  the  expansion 
being  utilized  as  the  motive  power. 

An  internal  combustion  engine  can  use  various  kinds  of 
fuel,  but  all  of  them  are  hydrocarbons.  Heavy  oils  are  not 
much  used  in  motor  car  practice  except  on  heavy  vehicles; 
and,  for  the  sake  of  description,  we  shall  take  it  that  the  inter- 
nal combustion  engine  used  in  the  automobile  will  burn  the 
very  light  hydrocarbon  known  as  gasolene  or  petroleum 
spirit.  It  is  from  this  that  the  gas  is  produced  which  is  burned 
inside  the  engine. 

The  production  of  the  gas  from  the  hydrocarbon  is  the 
^unction  of  the  carbureter.  (See  Carbureter.)  The  gas,  being 


20  MOTORS  AND  MECHANISM 

expansive  or  explosive  when  ignited,  is  used  to  force  a  piston 
in  a  cylinder  outward,  this  piston  being  connected  by  means 
of  a  connecting  rod  to  the  crank  in  such  a  manner  that  when 
it  is  forced  out  by  the  expansion  of  the  gas  in  the  cylinder  it 
turns  the  crank ;  but  the  mechanism  which  is  required  to  pro- 
duce this  apparently  simple  operation  has  other  Junctions  to 
perform.  Before  the  gas  can  be  exploded  in  the  cylinder,  it 
is  necessary  to  draw  it  in,  which  means  that  there  must  be 
some  opening  in  the  cylinder  through  which  it  may  pass.  Be- 
fore it  can  be  exploded  so  that  it  will  drive  the  piston  down  in 
the  cylinder,  there  must  be  some  means  of  closing  up  the 
entrance  through  which  it  has  passed  into  the  cylinder;  while, 
again,  before  the  operation  of  exploding  the  gas  can  be  re- 
peated, it  is  essential  to  get  rid  of  the  exhaust  gases  gener- 
ated by  the  explosion.  Also,  some  method  of  igniting  the 
gas  so  as  to  cause  it  to  expand  must  be  provided.  This  latter 
requirement  is  usually  attained  by  means  of  an  electric  spark. 

Anoth  :r  fact  to  be  noted  is  that  the  explosive  gas  drawn 
into  the  cylinder  will  give  out  greater  power  when  ignited  if 
it  is  first  compressed,  and  therefore  the  engine  has  also  to 
perform  the  function  of  compressing  the  charge.  Thus  the 
engine  has  four  different  duties  to  perform: 

First,  it  has  to  open  the  inlet  valve  and  to  draw  in  the 
charge. 

Second,  it  has  to  close  the  inlet  and  compress  the  charge. 

Third,  it  has  to  fire  the  charge  so  as  to  force  the  piston  out- 
ward to  do  work. 

Fourth,  it  has  to  expel  the  burnt  gases. 

It  is  owing  to  these  four  operations  having  to  be  performed 
in  sequence  that  the  internal  combustion  engine,  as  used  in 
automobiles,  is  known  as  a  "four-cycle"  engine. 

In  our  illustrations,  Figs.  I,  2,  3  and  4,  we  show  in  diagram- 
matic form  the  type  of  internal  combustion  engine  usually  ap- 
plied to  automobiles.  In  arrangement  of  details  engines  vary 
considerably,  but  in  the  main  features  they  are  all  practically 
alike.  A  is  the  cylinder  and  B  is  the  piston.  This  piston  B 
is  capable  of  sliding  freely  up  and  dnwn  inside  the  cylinder  A, 


MOTORS  AND  MECHANISM 


21 


but  it  is  provided  with  spring  rings,  which  prevent  any  gas 
passing  by  it.  D  is  the  connecting  rod  which  connects  the 
piston  to  the  crank  E,  which  crank  forms  part  of  the  engine 
shaft,  and  it  is  by  the  rotation  of  this  that  the  car  is  driven. 
The  piston  B,  when  it  is  forced  down  in  the  cylinder,  pushes 
round  the  crank  E,  and  so  turns  the  shaft.  F  and  Fi  are, 
respectively,  the  inlet  and  exhaust  valves. 

The  gas  from  the  carbureter  enters  at  G,  and,  after  having 
been  ignited,  is  expelled  through  the  port  Gi.    The  valves  F 


SUCTION  STROKE,  COMPRESSION  STROKR 

and  Fi  are  operated  by  the  engine  itself  by  means  of  cams 
H  and  Hi.  These  cams  are  carried  on  shafts  which  are  driven 
by  the  engine  crank  shaft,  but  at  half  its  speed.  The  dotted 
lines  indicate  the  gear  wheels  on  the  two  shafts  and  on  the 
engine,  by  means  of  which  the  shafts  are  rotated.  It  will  be 
seen  that  the  cam  on  either  of  these  shafts  will  lift  its  valve 
once  in  every  two  revolutions  of  the  crank  shaft. 

In  Fig.  i  we  see  that  the  cam  has  lifted  the  inlet  valve  F. 
At  the  same  time  the  crank  is  in  such  a  position  that  the 
piston  is  just  descending  in  the  cylinder.  As  the  piston  de- 
scends it  acts  as  a  suction  pump,  and  draws  in  the  gas  from 
the  carbureter  through  the  valve  port  G.  As  soon  as  the 


22 


MOTORS  AND  MECHANISM 


piston  has  reached  the  bottom  of  its  stroke  the  cam  H  allows 
the  valve  F  to  fall  on  its  seat.  The  flywheel  on  the  crank 
shaft  of  the  engine,  however,  through  its  stored  momentum, 
continues  to  rotate  the  crank,  and  therefore  the  piston  B  is 
pushed  back  again  into  the  cylinder  (Fig.  2),  but  as  now  there 
is  no  exit  from  the  cylinder,  the  gas  inside  it  is  compressed 
into  the  combustion  space.  This  compression  proceeds  until 
the  piston  has  reached  the  top  of  its  stroke,  and  at  this  point 
a  spark  is  caused  to  pass^icross  the  points  of  the  sparking  plug 
J.  As  soon  as  this  occurs,  the  gas  charge  is  ignited  and  ex- 


N°3 

POWER  STROKE.  EXHAUST  STROKE. 

pands  very  rapidly,  this  expansion  forcing  the  piston  B  down 
in  the  cylinder,  and,  through  the  medium  of  the  connecting 
rod,  turning  the  crank  E.  This  is  the  power  stroke  (Fig.  3). 

Immediately  before  the  piston  reaches  the  bottom  of  its 
stroke,  the  cam  Hi  lifts  the  exhaust  valve  Fi,  the  inlet  valve 
F,  of  course,  remaining  closed.  The  momentum  of  the  fly- 
wheel carries  the  crank  round  and  forces  the  piston  back  up 
the  cylinder,  it  in  turn  forcing  the  exhaust  gases  out  through 
the  exhaust  port  Gi.  This  is  the  exhaust  stroke  (Fig.  4).  The 
engine  is  now  in  a  position  to  perform  the  same  cycle  of  oper- 
ations as  before,  the  next  stroke  drawing  the  piston  down  and 


MOTORS  AND  MECHANISM  23 

bringing  in  a  fresh  charge  through  the  inlet  G,. which  in  turn 
is  compressed,  ignited  and  expelled  as  before.  It  will  thus 
be  seen  that  the  engine  during  two  revolutions  has  performed 
the  four  operations  which  are  necessary  to  its  proper  working. 
The  operations  in  sequence  are  as  follows: 
•  I.  Down  Stroke  of  the  Piston. — Gas  charge  is  drawn  in. 

2.  Up  Stroke  of  the  Piston. — Gas  charge  is  compressed. 

3.  Down  Stroke  of  the  Piston. — Gas  charge,  being  ignited, 
is  violently  expanding. 

4.  Up  Stroke  of  the  Piston. — The  exhaust  gases  are  being 
expelled. 

These  four  strokes  of  the  piston,  respectively,  are  known  as 
the.  Suction,  Compression,  Power  and  Exhaust  strokes,  as  in- 
dicated under  the  diagrams. 

As  the  initial  operation  is  to  draw  in  a  charge  of  gas,  it  will 
be  seen  that  before  the  engine  can  be  started  it  is  necessary 
to  rotate  the  crank  shaft  so  that  a  charge  is  drawn  in  and 
compressed.  This  is  then  fired,  and  the  engine  will  continue 
to  operate  automatically. 

The  action  of  the  engine  being  understood  from  the  study 
of  the  diagrams,  we  may  now  describe  a  typical  automobile 
engine.  The  engine  may  have  one  or  more  cylinders.  Four 
is,  however,  a  general  number,  and  the  engine  which  we  shall 
describe  is  a  four-cylindered  one.  Our  illustration  is  of  a 
four-cylinder  35  H.P.  engine.  Fig.  5  shows  it  in  cross-section 
through  one  cylinder;  that  is  to  say,  the  engine  is  shown 
cut  in  half  through  the  cylinder  and  valve  chests  and  through 
the  crank  case.  Here  we  have  again  what  was  described  in 
diagrammatic  form  in  Figs.  I  to  4,  but  this  is  the  actual  ar- 
rangement of  an  efficient  and  modern  automobile  engine.  Fig. 
6  illustrates  the  same  engine  in  section  longitudinally,  show- 
ing all  four  cylinders,  crank  shaft  and  flywheel.  In  both  these 
diagrams  we  shall  retain  the  same  letters  for  the  different  parts 
as  shown  in  diagrams  Figs.  I  to  4.  A  is  the  cylinder;  B  is 
the  piston  with  its  rings  C ;  D  is  the  connecting  rod,  and  E  is 
the  crank.  The  rings  C  around  the  piston  are  made  of  spring 
cast-iron,  and  by  their  own  springiness  they  hold  tightly  up 


MOTORS  AND  MECHANISM 


FIG.  5— CROSS  SECTION  OF  A  35  H.  P.  ENGINE. 
Index  to  Figs.  5,  6  and  7. 

O,  Crank  case.  * 


'A,  Cylinder. 
fc,  Piston. 

C,  Piston  rings. 

D,  Connecting  rod. 

E,  Crank. 

Ei,  Ei,  Ex,  Ei.  Crank  pins. 

Ea,  £2,  £2,  £2,  Radial  oil  leads  on 

big  end  bearings. 
£3,  £3,  £3.  £3,  Holes  for  ejecting 

oil  from  big  end  bearings. 

F,  Inlet  valve. 
Ft,  Exhaust  valve. 
CJ,  Inlet  port. 

Gi,  Exhaust  port. 

H,  Inlet  cam. 

Hi,  Exhaust  cam. 

Ha,  Oil  pump  cam. 

H3,  Oil  pump  plunger. 

tlj.  Spring  keeping  oil  pump  plunger 

in  contact  with  cam  Ha. 
HS,  Automatic  delivery  valve  to  oil 


L,  Water  pump  (in  dotted  lines). 
M,  Water  inlet. 
N.  Water  outlet. 


P,  Oil  pump. 

Q,  Compression  tap. 

R,  R,  Valve  springs. 

S,  Valve  plunger. 

T,  Roller  on  valve  plunger. 

U,  Crank  shaft. 

V,  V,  V,  Crank  shaft  main  bearings. 

W,  &y-wheel. 

Wi,  Coupling  on  fly-wheel  to  crank 

X,X,X,Oil  leads  to  main  bearings. 
Xi,  Xi,  Xi,  Radial  holes  leading 

from  main  bearings  to  crank 

shaft  centre. 
Y  and  Y,  Ball  thrust  bearings  on 

forward  main  bearing  to  crank 

shaft 

Z,  Pinion  wheel  on  crank  shaft. 
T.I,  Intermediate  pinion. 
Zr,  One   of  the  two   gear  wheels 

meshing      with      intermediate 

pinion  Zi,  and  driving  the  inlet 

and  exhaust  cam  shafts. 
Zj,  Oil    sump    from    which    oil    i» 

drawn,  to  the  pump. 


MOTORS  AND  MECHANISM  25 

against  the  wall  of  the  cylinder  in  such  a  way  as  to  prevent 
the  passage  of  any  gas. 

An  illustration  of  a  piston  is  shown  at  Fig.  5A,  though  this 
is  not  the  piston  of  the  engine  we  are  describing.  It  will  be 
seen  that  there  are  three  rings  in  grooves.  These  rings  are 
slotted,  as  shown,  diagonally.  The  diagonal  slot  in  the  center 
ring  is  not  shown  in  our  illustration,  as  it  is  behind  the  piston. 
The  rings  are  normally  bigger  than  the  inside  of  the  cylinder, 
but  when  contracted  so  that  the  diagonal  slots  are  closed  up, 
they  will  fit  inside  the  cylinder,  and  will  keep  tight  against  it 
owing  to  their  tendency  to  spring  outward.  These  slots  in 


FIG.  SA— PISTON  WITH  RINGS. 

the  piston  are  kept  an  equal  distance  apart  so  as  to  preclude 
the  passage  of  gas. 

Returning  to  Fig.  5,  F  is  the  inlet  valve  and  Fi  the  exhaust 
valve,  while  G  and  Gi  are,  respectively,  the  inlet  an'd  exhaust 
ports.  H  is  the  inlet  valve  cam,  and  Hi  is  the  exhaust  valve 
cam.  These  are  on  shafts  which  are  driven  by  gear  wheels 
from  the  engine,  indicated  by  the  dotted  lines,  but  shown  in 
position  at  Z,  Zi  and  Z2  in  Fig.  6.  J  is  the  sparking  plug. 
It  will  be  seen  that  around  the  cylinder  and  around  the  valves 
there  is  a  pocket  or  jacket  K  (Fig.  6).  This  jacket  is  used 
for  keeping  the  cylinders  at  a  temperature  at  which  the  engine 
will  work  efficiently,  and  water  is  circulated  through  the 
jacket  from  a  pump,  shown  in  outline  at  L,  which  forces  water 
up  through  the  pipe  M  and  out  at  the  top  of  the  jacket  through 
the  pipe  N.  One  jacket  is  used  for  one  pair  of  cylinders,  and 


26  MOTORS  AND  MECHANISM 

another  jacket  for  the  other  pair,  as  is  shown  quite  clearly 
in  Fig.  6. 

The  crank  shaft  of  the  engine  is  carried  in  bearings  which 
are  fixed  in  the  crank  case  O.  This  case  is  made  of  aluminum, 
and  not  only  incloses  the  engine,  cam  shafts  and  gearing,  but 
is  also  used  to  assist  in  the  lubrication,  which  is  a  most  im- 
portant feature  of  all  internal  combustion  engines.  For  this 
purpose  there  is  an  oil  pump  P  driven  by  the  engine,  and 
shown  in  Fig.  7,  to  which  we  shall  shortly  refer.  This  pumps 
oil  out  of  the  bottom  of  the  crank  case  O,  and  forces  it  to  the 
various  bearings  cf  the  engine.  At  Q  is  shown  a  valve,  tap  or 
cock,  known  as  the  compression  cock.  By  opening  this,  kero- 
sene can  be  injected  into  the  cylinder  for  the  purpose  of  facili^ 
tating  starting,  and  at  the  same  time  the  compression  will  be 
released,  as,  while  this  is  open,  the  rising  piston  will  force  the 
gas  or  air  out  through  this  valve.  It  will  be  seen  that  the 
valves,  both  inlet  and  exhaust,  are  kept  down  on  their  seats 
by  means  of  springs  R,  R.  The  cams  lift  them  through  the 
medium  of  plungers  S,  S,  these  plungers  being  arranged  with 
an  adjustable  screw  by  means  of  which  the  lift  of  the  valves 
may  be  regulated.  At  their  ends  they  carry  rollers,  one  of 
which  is  shown  at  T,  and  it  is  against  these  rollers  that  the 
cams  work. 

Referring  now  to  Fig.  6,  which  shows  the  same  engine  in 
section  longitudinally,  we  can  see  the  arrangement  of  the 
cranks,  connecting  rods  and  the  gear  which  drives  the  two 
cam  shafts — one  at  either  side  of  the  engine.  (Here,  again, 
the  same  reference  letters  are  used  to  denote  similar  parts 
to  those  in  Fig.  5.)  In  this  illustration  it  can  be  seen  that 
the  two  cylinders  of  each  pair  are  cast  in  one  piece,  with  one 
water  jacket  K  surrounding  them.  This  view,  of  course,  does 
not  show  the  valve  chambers,  as  these  are  on  each  side  of  the 
cylinders. 

Shaft  U,  as  will  be  seen,  runs  through  'three  main  bearings, 
V,  V,  V.  These  bearings  are  of  special  anti-friction  metal. 
At  the  end  of  the  crank  shaft  is  the  flywheel  W,  which  is  at- 
tached to  the  crank  shaft  by  means  of  the  flange,  formed  in 


MOTORS  AND  MECHANISM 


27 


28  MOTORS  AND  MECHANISM 

one  with  the  crank  shaft,  and  the  bolts  and  nuts,  one  pair 
of  which  is  shown  at  Wi. 

The  main  bearings  are  carried  in  brackets  which  are  sus- 
pended from  the  top  of  the  crank  case,  and  in  order  to  lubri- 
cate these  there  are  oil  leads  X,  X,  X.  These  oil  leads  are 
connected  to  the  pump  (which  is  illustrated  at  P  in  Fig.  5). 

In  order  to  take  up  any  end-thrust  on  the  crank  shaft  when 
the  clutch  is  released,  there  are  ball-thrust  bearings  shown  at 
Y  just  behind  the  forward  main  bearing  of  the  engine,  and 
in  front  of  this  bearing. 

Two  connecting  rods  D,  D,  from  each  pair  of  cylinders, 
drive  on  two  crank  pins  between  the  center  and  forward  bear- 
ings, and  similarly  between  the  center  and  after-bearing — 
this  arrangement  allowing  a  very  wide  bearing  to  the  crank 
pins. 

At  Z  is  shown  the  pinion  wheel  which  is  attached  to  the 
end  of  the  crank  shaft  U.  This  pinion  wheel  drives  the  inter- 
mediate pinion  Zi,  which,  in  turn,  is  in  gear  with  two  larger 
gear  wheels,  one  of  which  is  shown  at  Z2.  One  of  these  gear 
wheels  is  attached  to  the  inlet  valve  cam  shaft,  and  the  other 
to  the  exhaust  valve  cam  shaft. 

The  Eight  Cylinder  Motor. 

With  a  single  cylinder  four-stroke  cycle  motor  there  is  one 
power  impulse  in  every  two  revolutions,  and  as  this  im- 
pulse must  be  heavy  enough  to  carry  the  load  during  the 
remainder  of  the  period  there  is  a  tremendous  shock  to  the 
passengers  and  to  the  mechanism  at  every  explosion.  If  two 
cylinders  are  used  there  is  an  impulse  every  revolution,  the 
force  of  which  need  be  only  one-half  of  that  of  the  single 
cylinder.  The  driving  is  more  uniform  because  the  power 
is  applied  more  frequently  and  the  stresses  induced  in  the 
frame  are  only  half  of  those  in  the  first  case. 

Therefore,  increasing  the  number  of  cylinders  for  a  given 
power  decreases  the  shock  per  individual  impulse,  giving  bet- 
ter explosion  balance  and  better  and  smoother  drive  or 
"torque."  In  addition  to  giving  better  explosion  balance  it  is 


MOTORS  AND  MECHANISM 


29 


30  MOTORS  AND  MECHANISM 

also  possible  to  obtain  better  mechanical  balance  with  the 
reciprocating  parts  since  the  movement  of  the  parts  of  one 
cylinder  can  be  made  nearly  equal  and  opposite  to  the  move- 
ment of  the  parts  in  the  others. 

A  six  cylinder  motor  has  three  power  impulses  per  revolu- 
tion, while  an  eight  cylinder  motor  has  four,  thus  the  eight 
has  a  33  per  cent  more  uniform  drive  or  torque  than  a  six. 
Because  of  this  continuous  application  of  driving  effort  the 
machine  can  be  throttled  down  very  low  on  high  gear  and 
will  accelerate  rapidly  even  on  steep  hills. 

Assuming  that  the  most  active  part  of  the  working  or 
impulse  stroke  lasts  75  per  cent  of  the  entire  stroke,  it  will 
be  seen  that  there  are  at  all  times  two  very  active  cylinders  at 
work  on  the  crankshaft.  For  this  reason  a  very  light  fly-wheel 
can  be  used  as  ft  has  to  store  very  little  power. 

With  this  uniform  drive  always  at  command  there  is  very 
little' necessity  for  changing  gears  when  threading  through 
the  traffic  of  crowded  city  streets  or  in  climbing  grades.  The 
speed  variation  is  from  about  75  revolutions  per  minute  to 
3,000,  obtained  entirely  by  throttle.  With  the  Cadillac  this 
corresponds  to  a  speed  range  of  2%  to  60  miles  per  hour 
without  touching  the  gear  shift  lever. 

As  there  are  only  four  cylinders  in  a  row,  the  length  of  the 
eight  is  the  same  as  the  four  and  about  -25  per  cent  less  than 
the  six,  with  equal  bores.  Since  there  are  more  cylinders,  the 
bore  is  less  for  equal  power,  which  brings  the  length  still  less 
in  comparison.  A  decrease  in  length  permits  either  a  shorter 
wheelbase  or  more  body  room  for  the  passengers  with  an 
equal  wheelbase.  Again,  the  crankshaft  is  shorter  than  the 
six,  making  it  possible  to  run  successfully  with  two  end  bear- 
ings and  still  retain  a  small  shaft  diameter  that  is  .free  from 
the  disturbances  that  occur  in  long,  limber  crankshafts. 

The  crank-throws  being  all  in  the  same  plane,  an  eight 
cylinder  crankshaft  is  as  easy  to  machine  as  that  of  a  four, 
and  is  far  cheaper  than  the  shaft  of  a  six.  A  short  camshaft 
is  particularly  desirable  as  it  is  free  from  the  torsional  deflec- 


MOTORS  AND  MECHANISM  31 

tions  of  a  long  shaft  which  causes  relative  changes  in  the 
firing  order. 

While  the  cylinder  blocks  of  an  eight  cylinder  motor  weigh 
about  15  per  cent  more  than  a  six  en  bloc,  this  weight  is  more 
than  offset  by  the  reduction  in  length  of  the  two  heaviest 


TYPICAL  EIGHT  CYLINDER  MOTOR  (FRONT  VIEW). 

Each  Cylinder  Block  is  Inclined  at  45  Degrees  with  Vertical  Center  Line  and  Con- 
tains Four  Cylinders. 

items,  the  crank-case  and  crankshaft.  A  six  cylinder  crank- 
case  is  very  expensive  as  it  is  long  and  requires  much  metal 
for  stiffness. 


32  MOTORS  AND  MECHANISM 

All  of  the  reciprocating  parts  are  light,  a  most  important 
feature,  since  reciprocating  forces  add  weight  doubly  through 
their  inertia,  causing  stresses  in  the  frame  that  must  be  re- 
sisted by  increasing  the  metal.  The  small,  light  valves  cause 
very  little  wear. 

The  cylinder  of  the  eight  being  of  small  bore  presents  more 
radiating  surface  per  unit  cylinder  volume  than  with  a  large 
cylinder,  thus  causing  a  greater  loss  of  heat  to  the  water 
jacket.  This  is  overcome  by  the  fact  that  a  higher  compres- 
sion pressure  can  be  carried  with  a  small  cylinder  which  makes 
the  eight  equal,  if  not  superior,  to  the  six  in  efficiency. 

Cadillac  Eight  Cylinder  Car. 

The  Cadillac  eight  cylinder  motor  has  a  bore  and  stroke  of 
31/8x5%  inches,  giving  an  S.  A.  E.  rated  horsepower  of  31.28, 
the  total  piston  displacement  being  314  cubic  inches. 

It  is  of  the  "V"  type  having  two  blocks  of  four  cylinders 
inclined  at  an  angle  of  90  degrees  with  one  another.  As 
the  two  blocks  are  directly  opposite  the  total  length  of  the 
engine  is  no  greater  than  that  of  a  four  cylinder  of  equal  bore. 
Both  blocks  act  on  a  four-throw  crankshaft  which  is  identi- 
cal in  construction  to  a  four  cylinder  three-bearing  shaft,  this 
being  a  much  simpler  manufacturing  proposition  than  the  six 
cylinder  shaft  and  in  addition  is  fully  one-third  lighter. 

Externally  the  cylinder  blocks  are  similar  in  appearance  to 
the  ordinary  en  bloc  four,  and  are  fastened  to  the  aluminum 
crank-case  in  the  same  way.  The  cylinders  are  of  the  "L" 
head  type,  the  valves  receiving  their  motion  from  a  single  cam- 
shaft located  in  the  top  of  the  crank-case  midway  between  the 
two  blocks.  Two  independent  exhaust  pipes,  one  from  each 
block,  lead  to  the  extreme  end  of  the  car  and  are  connected  at 
the  motor  end  to  an  integrally  cast  manifold. 

As  the  cylinders  of  the  two  blocks  are  directly  opposite,  and 
as  opposite  cylinders  act  on  the  same  crank  throw,  it  is  evi- 
dent that  the  connecting  rods  must  be  of  special  cpnstruction. 
To  meet  this  awkward  problem  one  of  the  rods  is  of  a  clevis 
form,  the  opposing  rod  coming  between  the  jaws  of  the  clevis. 


MOTORS  AND  MECHANISM 


33 


The  bronze  crank  pin  bushing  is  fastened  rigidly  to  the  jaws 
while  the  other  connecting  rod  slides  freely  on  the  outside  of 
the  bushing,  the  outside  and  inside  of  the  bushing  both  pro- 
viding bearing  surfaces  for  the  crank  pin  and  connecting  rod. 

A  single  camshaft  is  located  directly  above  the  crankshaft 
and  is  provided  with  eight  integral  cams,  four  of  which  are 
wide  faced  so  as  to  receive  the  rollers  of  four  rocker  arms. 


EIGHT  CYLINDER  CADILLAC  MOTOR. 

One  cam  operates  two  inlet  valves  or  exhaust  valves,  as  the 
case  may  be. 

Directly  above  the  camshaft  is  the  shaft  used  for  the  Delco 
self-starting  motor  generator  and  which  also  carries  the  fan. 
This  is  driven  by  a  silent  chain  from  the  double  sprocket  on 
the  camshaft.  A  tire  pump  is  driven  by  a  gear  that  can  be 
meshed  at  will  with  a  gear  mounted  on  the  generator  shaft, 
the  pump  being  above  and  to  the  front  of  the  generator. 


34  MOTORS  AND  MECHANISM 

At  the  front  and  below  the  crankshaft  is  a  transverse  shaft 
driven  by  spiral  gears  which  carries  a  circulating  pump  at 
either  end,  one  pump  for  each  block.  A  third  spiral  meshing 
with  the  water  pump  gear  drives  the  oil  pump. 

Probably  one  of  the  most  interesting  features  of  the  water 
circulating  system,  aside  from  the  double  pump  system,  is  the 
thermostatic  circulation  control  with  which  the  circulating 
water  is  kept  at  a. constant  temperature.  A  thermostat,  con- 
sisting of  a  tube  rilled  with  a  volatile  liquid,  is  placed  in  the 
water  pump  line.  This  controls  the  water  by  means  of  a  valve. 
When  the  water  is  too  warm  the  thermostat  expands,  opens 
the  valve  and  allows  more  water  to  pass  through  the  radiator. 
A  by-pass  connected  with  this  system  also  connects  with  the 
water-jacket  of  the  carbureter  in  such  a  way  that  when  the 
water  is  cold  and  the  valve  closed,  the  water  will  pass  through 
the  carbureter.  When  starting  with  the  valve  closed  all  of 
the  water  passes  through  the  carbureter  and  none  through 
the  radiator,  thus  giving  the  carbureter  the  first  chance  at  the 
warm  water.'  In  this  way  there  is  only  a  small  amount  of 
water  circulating  at  the  start  which  causes  rapid  heating  of 
the  cylinders  and  carbureter.  When  the  temperature  is  built 
up  to  the  required  degree,  the  valve  opens  and  a  certain 
amount  passes  to  the  radiator. 

Oil  is  supplied  by  a  gear  pump  to  a  reservoir  pipe  running 
inside  of  the  crank  case  from  which  there  is  a  lead  to  each 
main  bearing.  The  oil  is  forced  from  the  main  bearings  to 
the  connecting  rod  ends  through  holes  drilled  in  the  pins. 
From  a  connection  in  the  reservoir  pipe  the  oil  enters  a  relief 
valve  which  maintains  a  constant  oil  pressure.  The  pistons 
are  lubricated  by  splash. 

A  Delco  unit  is  used  for  self-starting,  lighting  and  ignition, 
the  eight  cylinder  high  tension  distributer  being  built  in  a 
unit  with  the  motor  generator. 


MOTORS  AND  MECHANISM  35 


CHAPTER  III 

ANALYSIS  OF  MOTOR  PARTS  AND  THE  COOLING 

SYSTEM 

Connecting  Rod  Bearings. 

Near  the  closed  end  of  the  piston  is  mounted  a  spindle, 
the  gudgeon  or  piston  pin.  The  upper  end  of  the  connecting 
rod  rocks  on  this  pin,  and  it  is  important  that  the  pin  itself 
should  not  move,  and  that  the  means  for  fixing  it  should  not  get 
loose  and  drop  away,  or  considerable  damage  may  be  done. 
It  is  not  within  our  scope  to  detail  all  the  devices  that  have 
been  employed,  but  one  of  the  simplest  is  to  form  one  of  the 
piston  ring  grooves  coincident  with  the  ends  of  the  gudgeon 
pin  which  extends  right  through  the  walls  of  the  piston.  As 
the  piston  and  connecting  rod,  being  reciprocating  parts,  are 
subject  to  innumerable  and  sudden  reversals  of  their  direction 
of  motion,  they  should  be  made  as  light  as  possible,  consis- 
tently with  being  strong  enough  to  withstand  the  explosions 
and  convert  the  impulses  into  a  rotary  motion  of  the  crank- 
shaft. The  gudgeon  pin  end  of  the  connecting  rod  is  called 
the  .small  end,  and  the  other  the  big  end.  The  journals,  or 
bearings,  at  the  big  end  are  adjustable,  so  that  wear  may  be 
taken  upr  from  time  to  time. 

The  Crank  Case. 

The  crankshaft  is  mounted  in  bearings  in  a  casing  called  the 
crank  case.  The  case  is  usually  made  of  aluminum  alloy  for 
lightness ;  and,  with  bracket  extensions,  it  forms  a  means  of  at- 
taching the  engine  to  the  frame  of  the  car ;  it  also  serves  as  an 
oilbath,  into  which  the  cranks  dip  as  they  rotate  and  splash  the 
oil- about  so  that  a  quantity  falls  into  little  ducts  which  lead  to 
the  bearings.  The  crank  case  should  be  made  with  handholes, 
through  which  the  big  end  bearings  may  be  adjusted ;  if  they 
are  large  enough  to  allow  of  withdrawing  the  piston,  so  much 


36  MOTORS  AND  MECHANISM 

the  better.  Another  arrangement  is  to  divide  the  crank  case 
horizontally,  and  fix  the  crankshaft  bearings  to  the  upper  part 
of  the  case.  This  allows  of  the  lower  portion  of  the  case  be- 
ing detached  without  disturbing  anything  else,  and  when  this 
part  is  removed,  those  above  it  can  be  dealt  with  as  may  be 
required.  A  combination  of  the  two  plans  is  best;  as  -the 
second  one  entails  a  lot  of  upside-down  working. 

Where  the  crankshaft  has  more  than  two  cranks,  there 
should  be  a  bearing  on  each'  side  of  each  pair  of  cranks,  other- 
wise there  is  a  danger  of  the  crankshaft  bending,  and  even 
breaking,  under  its  work. 

Function  of  the  Half-speed  Shaft. 

As  each  operation  of  the  motor  happens  only  once  in  two 
revolutions  of  the  crankshaft,  the  firing  of  the  charge  and  the 
opening  of  the  exhaust  valve  are  controlled  by  a  shaft  rotated 
at  half  the  speed  of  the  crankshaft.  For  this  'purpose  gear 
wheels  are  fixed  to  the  crankshaft  and  to  the  "half-speed 
shaft" ;  these  wheels  gear  together,  and  the  wheel  on  the  half- 
speed  shaft  has  twice  as  many  teeth  as  the  wheel  on  the  crank- 
shaft. On  the  half-speed  shaft  is  fixed  a  cam,  that  is,  a  ring 
or  collar  bearing  a  hump  or  projection  on  its  periphery. 
On  this  cam  stands  a  rod  or  plunger,  and  this  plunger  is  in 
line  with  the  stem  of  the  exhaust  valve.  Hence,  at  every  revo- 
lution of  the  half-speed  shaft  (and  so  at  every  alternate  revolu- 
tion of  the  crankshaft),  the  cam  comes  round  and  lifts  the  ex- 
haust valve,  through  the  plunger. 

The  Exhaust  Valve. 

It  should  be  pointed  out  that  the  term  valve  is  used  to  ex- 
press both  a  whole  and  a  part.  In  the  larger  sense  the  "valve" 
means  both  the  door  and  its  frame — the  disk  and  its  seating; 
in  its  smaller  sense  it  means  the  door  or  disk  only.  From  the 
form  of  the  disk,  and  the  stem  under  the  disk,  this  type  of  valve 
is  called  a  mushroom  valve.  Owing  to  the  length  of  the  stem 
used  in  motors,  the  valve  looks  perhaps  more  like  a  flat-headed 
nail  than  a  mushroom.  The  seating  forms  a  shoulder  in  a 
passage  communicating  with  the  combustion  chamber  on  the 


MOTORS  AND  MECHANISM  37 

one  hand  and  the  exhaust  pipe  on  the  other.  Sometimes  the 
exhaust  valve  is  arranged  directly  over  the  combustion  space  in 
the  cylinder  head,  but  more  often  it  is  arranged  in  an  exhaust 
valve  box  at  the  side  of  the  cylinder.  The  upper  part  of  the 
stem  works  in  a  guide,  and  a  plate  or  washer  is  mounted  on 
the  lower  part  of  the  stem.  Between  the  guide  and  the  washer 
there  is  a  strong  spring,  which  normally  holds  the  valve  tight 
down  on  its  seating.  The  edge  of  the  valve  and  the  seating 
are  generally  beveled,  and  carefully  ground  to  the  same  angle, 
so  that  the  valve  may  be  gastight  when  closed.. 

It  will  be  remembered  that  the  exhaust  valve  is  only  open 
during  one  of  the  return  strokes  of  the  piston.  This  corre- 
sponds to  half  a  turn  of  the  crankshaft,  and  to  a  quarter  of  a 
turn  of  the  half-speed  shaft.  Hence  the  hump  only  occupies 
about  a  quarter  of  the  periphery  of  the  cam.  In  practice,  it  is 
for  nd  best  to  allow  the  exhaust  valve  to  open  before  the  piston 
has  quite  finished  its  driving  stroke,  and  to  close  exactly  at 
the  top  of  the  return  stroke.  The  valve  should  open  fully  and 
close  completely  as  promptly  as  possible,  but  each  end  of  the 
hump  must  be  inclined — the  forward  end  to  lift  the  valve 
plunger  in  ordinary  running,  the  rearward  end  to  do  the  same 
in  case  the  engine  is-  accidentally  reversed.  Were  it  not  for 
this  last  consideration,  the  hump  might  have  a  radial  or  pre- 
cipitous end.  Sometimes  a  hinged  arm  is  interposed  between 
the  surface  of  the  cam  and  the  foot  of  the  plunger ;  this  is  use- 
ful in  overcoming  the  transverse  action  set  up  by  the  inclines 
when  operating  directly  on  the  plunger,  and  (when  an  adjust- 
able arm  is  used)  in  providing  means  for  controlling  the  motor 
by  varying  the  lift  of  the  valve.  The  exhaust  passage  or  port, 
the  valve  itself,  and  the  exhaust  pipe  should  be  of  ample  di- 
mensions, so  that  the  exhaust  gases  may  be  cleared  out  with 
as  little  resistance  as  possible.  A  good  many  motors  are  now 
constructed  with  a  large  chamber,  into  which  the  exhaust  ports 
of  all  the  cylinders  open.  This  provides  for  more  ready  ex- 
pansion of  the  gases  than  if  they  are  led  directly  into  the  more 
or  less  restricted  exhaust  pipe. 

When  the  cylinders  of  the  engine  are  separate  castings,  the 


38  MOTORS  AND  MECHANISM 

branches  of  the  exhaust  pipe  should  b'e  connected  in  such  a 
way  as  to  allow  for  a  slight  relative  movement  due  to  unequal 
expansion  of  the  cylinders. 

Silencing  the  Exhaust. 

The  object  of  the  exhaust  box  is  to  silence  or  muffle  the 
noise  of  the  exhaust.  At  the  same  time  it  must  allow  of  the 
ultimate  egress  of  the  gases  as  freely  as  possible,  otherwise  it 
will  set  up.  a  back  pressure,  which  will  reduce  the  effective 
power  of  the  engine.  In  the  box  are  a  number  of  tubes  or 
plates,  which  turn  the  stream  of  exhaust  gases  first  one  way 
and  then  another,  as  in  a  maze,-  allowing  them  all  the  time  to 
expand  more  and  more,  and  ultimately  allowing  them  to  pass 
out  through  a  number  of  fine  holes  or  a  pipe.  These  holes,  or 
the  pipe,  should  not  point  directly  toward  the  ground ;  if  they 
do,  the  exhaust  will  greatly  augment  the  dust  raised;  and  if 
they  point  backward  it  is  very  unpleasant  for  anyone  behind, 
during  a  block  in  traffic.  The  box  should  be  of  good  di- 
mensions; and  should  be  carried  under  the  back  part  of  the 
car,  so  that  the  occupants  may  not  be  troubled  by  any  fumes 
emitted  by  it.  Do  not  forget  that  the  exhaust  pipe  and  box 
get  extremely  hot,  and  nothing  liable  to  be  damaged  by  heat 
(fingers,  tires,  eatables,  etc.)  should  be  brought  near  them. 

The  Inlet  Valve. 

The  inlet  valve  may  be  opened  either  by  the  suction  of  the 
piston,  or  positively  like  the  exhaust  valve.  In  the  former 
case  no  special  mechanism  is  required ;  the  valve  is  made  very 
light,  and  is  normally  held  closed  by  a  comparatively  weak 
spring.  Some  prefer  the  automatic  valve  for  high-speed  work, 
and  it  is  certainly  simpler  than  the  mechanically-operated 
valve.  Where  the  latter  form  is  employed,  it  is  operated  by  a 
cam  on  a  half-speed  shaft  like  the  exhaust  valve.  In  fact,  the 
valve  parts  can  be  made  duplicates  of  each  other,  thus  reduc- 
ing the  number  of  spare  parts  that  should  be  carried.  The 
contention  that  an  engine  with  mechanically-operated  inlet 
valves  can  be  run  slower  than  one  with  automatic  inlet  valves 
is  to  some  extent  supported  by  practice ;  any  way,  the  former 


MOTORS  AND  MECHANISM  39 

are  more  often  used  than  the  latter.  But,  however  the  valve 
is  operated,  the  charge  is  drawn  into  the  cylinder  by  the  so- 
called  suction  of  the  piston. 

The  inlet  valve  is  arranged  in  the  port  or  passage  connect- 
ing the  inlet  pipe  with  the  combustion  space.  When  it  is  lo- 
cated in  the  cylinder  head,  and  is  mechanically  operated,  the 
stem  is  directed  upwards,  and  is  operated  on  by  one  end  of  a 
rocking  or  see-saw  arm,  the  other  end  of  the  arm  being  actu- 
ated by  a  long  plunger  rod.  More  often,  however,  the  inlet 
valve  is  set  head  upward,  like  the  exhaust  valve,  and  is  worked 
by  a  cam  and  short  plunger.  The  inlet  valves  with  their  boxes 
may  be  arranged  on  the  same  side  of  the  cylinders-as  the  ex- 
haust valves,  in  which  case  they  are  all  operated  from  cams 
on  a  single  shaft.  This  keeps  down  the  number  of  parts,  but 
crowds  them  together  rather,  and  generally  involves  a  long 
and  tortuous  inlet  pipe,  in  addition  to  a  tendency  to  unduly 
heat  and  therefore  rarefy  the  induced  charge.  If  the  inlet 
valves  are  arranged  on  the  other  side  of  the  cylinders,  a  sec- 
ond half-speed  gear  and  shaft  are  necessary,  but  the  various 
parts  are  rendered  more  easily  accessible,  and  the  timing  of 
the  exhaust  and  inlet  valves  can  be  regulated  independently. 
This  timing  is  a  very  important  matter,  as,  unless  the  valves 
open  and  close  just  at  the  right  times,  the  engine  will  not  give 
off  its  full  power.  The  close  fitting  of  the  valve  head  on  to 
its  seating  is  also  important,  and  to  facilitate  the  grinding-in 
of  the  valve,  the  head  should  be  provided  with  a  screwdriver 
slot.  If  the  valve  seatings  are  detachable,  the  grinding-in 
process  can  be  conducted  away  from  the  rest  of  the  engine, 
and  the  risk  of  the  abrasive  material  finding  its  way  into  the 
cylinder  is'  avoided. 

The  inlet  and  exhaust  ports  should  be  short,  and,  gener- 
ally, the  combustion  space  should  be  as  free  from  pockets  as 
possible,  as  these  tend  to  retain  portions  of  the  exhaust  gases 
which  mingle  with,  and  deteriorate,  the  incoming  charges  of 
combustible  gas.  Externally,  also,  the  motor  should  present  a 
clean  appearance,  and  all  fixings  should  be  well  secured  and 
readily  accessible 


40  MOTORS  AND  MECHANISM 

Cooling  System. 

Owing  to  the  intense  heat  generated  by  the  explosions  in 
the  cylinders  it  is  necessary  to  cool  the  cylinder  walls  in  order 
to  hold  lubricating  oil  on  the  interior  surfaces.  As  the  tem- 
perature of  the  burning  gases  is  in  the  order  of  3,000  degrees 
and  the  vaporizing  point  of  the  oil  is  generally  less  than  600, 
it  is  evident  that  a  great  amount  of  heat  must  be  removed. 
Unfortunately  the  necessity  of  cooling  the  walls  considerably 
reduces  the  efficiency  of  the  engine,  for  in  the  average  case 
from  25  to  30  per  cent  of  the  heat  generated  by  the  fuel  is 
wasted  in  the  water  jacket.  The  function  of  the  cooling  sys- 
tem is  therefore  not  to  keep  the  cylinders  cold  but  to  keep 
them  cool  enough  so  that  we  can  maintain  an  oil  film  on  the 
surfaces  of  the  bore.  At  present,  the  temperature  is  entirely 
dependent  on  the  vaporizing  temperature  of  the  lubricant. 

Cooling  can  be  performed  either  by  placing  radiating  ribs 
around  the  cylinders  to  increase  the  radiating  surface  or  by 
surrounding  the  cylinders  by  a  water  jacket.  When  cooling 
by  air  it  is  difficult  to  obtain  enough  effective  cooling  surface 
with  the  ribs,  especially  with  large  cylinders,  and  for  that  rea- 
son there  is  but  one  automobile  manufacturer  that  builds  air 
cooled  motors  as  a  standard.  .  With  rib  cooling  a  strong  cur- 
rent of  cold  air  must  be  constantly  maintained  by  a  fan. 

Merely  holding  the  water  in  the  jackets  would  not  keep  the 
cylinders  cool  for  long,  so  we  must  either  allow  a  stream  of 
cold  water  to  run  continuously  through  the  jackets  or  circu- 
late the  water  through  a  cooler  where  the  heat  may  be  dissi- 
pated. In  the  automobile  the  water  is  cooled,  after  passing 
out  of  the  water  jackets,  by  means  of  what  is  known  as  a 
"Radiator."  The  water  in  passing  through  the  radiator  is 
split  up  "by  a  number  of  small  tubes,  which  having  a  large 
surface  in  proportion  to  their  contents,  rapidly  radiate  the 
heat  from  their  surfaces  to  the  outside  air.  A  pump,  usually 
of  the  centrifugal  type,  forces  the  water  from  the  jackets  into 
the  radiator. 


MOTORS  AND  MECHANISM 


By  adding  radiating  fins  to  the  tubes  and  by  placing  the 
radiator  in  front  of  the  automobile  where  it  will  catch  the 
wind,  it  is  possible  to  remove  the  heat  rapidly  enough  to  keep 
the  cylinders  at  any  desired  temperature.  The  radiator  acts 
simply  as  an  extended  surface  of  the  cylinder  walls.  To  aid 


COOLING   SYSTEMS. 

the  cooling  and  to  keep  the  motor  cool,  when  the  car  is  stand- 
ing idle  with  the  motor  running,  it  is  necessary  to  install  a 
small  fan  just  back  of,  and  inside  of  the  hood.  This  is 
shown  by  the  accompanying  figure.  The  fan  may  be  either 
driven  from  the  motor  by  a  belt  or  gear,  although  the  most 
common  practice  is  to  belt  it  to  the  crankshaft. 


42  MOTORS  AND  MECHANISM 

In  Fig.  20  is  shown  a  system  of  the  type  described,  in  which 
C  is  the  water  jacket  of  the  cylinders,  P  is  the  pump,  R  is  the 
radiator,  and  E  is  the  fan.  The  pump  draws  the  water  from 
the  radiator  at  the  bottom,  G,  through  the  pipe  B  and  forces 
it  into  the  jacket  at  A.  It  now  passes  through  the  jacket  as 
shown  by  the  arrows  and  returns  to  the  radiator  through  the 
upper  water  manifold  D.  This  circulation  aided  by  the  radi- 
ator keeps  the  cylinders  cool.  The  wind  caused  by  the  motion 
of  the  car,  shown  by  arrows  H,  passes  through  the  radiator,  the 
force  of  the 'wind  being  assisted  by  the  fan  E.  The  system  is 
rilled  with  water  through  the  radiator  filler  Cap  F.  The  air  in 
passing  through  the  radiator  flows  over  the  engine  cylinders 
which  still  further  reduces  the  temperature. 

A  typical  centrifugal  pump  is  shown  by  Fig.  20A  in  which 
A  is  the  outer  casing  and  B  is  the  propeller  wheel.  Water 
enters  at  the  side  and  in  the  center  of  the  casing  at  C,  and  on 
coming  into  contact  with  the  wheel  is  thrown  outwardly 
against  the  casing  by  centrifugal  force.  This  force  caused 
by  the  rotation  of  the  water  forces  the  water  out  at  D  with 
considerable  pressure.  The  shaft  from  the  wheel  is  generally 
driven  from  the  camshaft  gears  or  from  the  camshaft. 

A  section  of  a  tubular  radiator  is  shown  by  Fig.  20-b  in 
which  B-B-B  are  the  tubes'  through  which  the  water  passes 
in  thin  sheets  in  the  direction  of  the  arrows  A-A-A.  The 
radiating  surface  is  increased  by  the  fins  F  which  are  soldered 
to  the  tube.  There  are  many  radiators,  widely  different  in 
the  arrangement  of  the  tubes,  but  this  is  a  simple  type  that 
is  extensively  used  and  will  serve  as  a  guide  to  other  con- 
structions. Theoretically,  the  thinner  the  sheet  of  water  in 
the  tube,  the  more  efficient  will  be  the  radiator,  but  practical 
reasons  limit  the  thinness,  the  principal  one  being  that  sedi- 
ment and  scale  would  soon  clog  a  passage  smaller  than  % 
inch. 

Thermo-Syphon  System. 

To  supply  the  circulating  system,  and  to  obtain  what  is  in 
some  respects  a  better  heat  distribution,  it  has  been  the 


MOTORS  AND  MECHANISM  43 

practice  with  several  prominent  makers  to  discard  the  pump 
and  to  depend  on  the  natural  circulation.  This  circulation, 
which  is  due  to  the  difference  in  temperature  between  the  top 
and  bottom  of  the  radiator  is  known  as  the  "Thermo-Syphon 
System,"  and  depends  for  its  operation  on  the  fact  that  warm 
expanded  water  is  displaced  by  the  heavier  colder  water  in 
the  radiator.  Fig.  21  shows  thermo-syphon  circulation.  The 
water  in  radiator  R  becomes  cooled  and  therefore  heavier 
than  the  warm  water  in  cylinder  jacket  C,  in  the  manifold  D, 
or  in  the  top  of  the  radiator,  and  its  weight  therefore  forces 
the  warm  water  up  and  into  the  upper  part  of  the  radiator. 
This  water  becomes  cooled,  and  the  action  continues.  For 
successful  thermo  circulation,  the  pipes  D  and  B  must  be  very 
large  in  diameter,  and  all  passages  free  and  easy  to  reduce  the 
friction.  As  the  pressure  causing  the  water  to  flow  is  very 
slight  when  compared  with  a  circulating  pump  the  greatest 
care  must  be  taken  to  eliminate  friction. 

The  thermo-syphon  system  has  the  advantage  that  the  rate 
of  circulation  is  in  proportion  to  the  heat  and  not  to  the 
engine  speed  as  in  the  case  of  the  pump.  When  the  engine  is 
running  slow  and  laboring  hard,  the  heat  is  at  a  maximum, 
but  with  the  pump  system  the  circulation  is  deficient  as  the 
pump  is  also  running  slow.  When  the  circulation  depends 
only  on  the  heat,  as  with  the  thermo  system,  the  cooling  and 
circulation  are  the  most  rapid  when  the  engine  is  hottest. 


44  MO  TORS  AND  MECHANISM 


CHAPTER  IV 
MOTOR  TRUCKS— GASOLINE  AND  ELECTRIC 

In  principle  the  gasoline  motor  truck  and  pleasure  car 
are  very  similar,  any  difference  between  the  two  lying  in  the 
arrangement  of  the  smaller  details  and  in  the  size  of  the  weight 
bearing  members.  In  fact  many  of  the  most  successful  light 
delivery  vehicles  are  built  on  a  chassis  nearly  identical  with 
the  pleasure  car  chassis  turned  out  by  that  particular  firm. 
With  the  heavier  trucks,  such  as  the  3  to  5  ton  types,  the 
low  speeds  and  heavy  loading  demand  changes  in  the  final 
drive,  in  the  type  of  tires,  method  of  control,  style  of  wheels 
and  in  the  weight  of  the  motor.  Every  gasoline  motor  truck 
has  the  following  elements  in  common  with  the  pleasure  car : 

Gasoline  Motor   (usually  four  cycle),  with  car- 
bureter, magneto,  muffler,  etc. 

Clutch,  for  giving  free  engine. 

Change  Gear  or  Transmission. 

Differential — Radiator — Throttle  Control. 
The  motor  is  usually  heavier  than  £>ne.  with  equivalent 
power  in  a  pleasure  car,  and  develops  its  rated  horsepower  at 
a  much  lower  speed,  which  power  for  power  means  a  larger 
bore  and  stroke.  The  low  speed  motor  is  the  result  of  the 
low  road  wheel  speed  used  with  the  truck  except  in  cases 
where  worm  drive  is  used.  In  the  majority  of  cases,  the  motor 
is  provided  with  an  automatic  governor  which  limits  the  speed 
of  the  vehicle  in  such  a  way  that  the  driver  cannot  force 
the  machine  above  a  certain  maximum  fixed  by  either  the 
maker  or  owner.  This  appliance  is  required  by  ordinance  in 
many  cities. 

The  ignition  may  be  by  any  system  commonly  used  by  the 


MOTORS  AND  MECHANISM  45 

pleasure  car,  but  with  the  difference  that  the  spark  is  either 
fixed,  or  automatically  advanced  and  retarded  by  mechanism 
within  the  system.  This  arrangement  takes  the  spark  adjust- 
ment out  of  the  hands  of  the  driver,  thus  giving  him  less  to 
attend  to  and  also  increases  the  efficiency  of  the  power  plant. 
The  advance  and  retard  handled  by  a  careless  driver  will  add 
enormously  to  the  fuel  consumption  and  total  cost  of  service. 

Motor  truck  transmissions  may  either  be  of  the  planetary 
or  sliding  type,  with  the  same  latitude  in  the  design  of  the 
clutch.  In  several  cases  the  power  of  the  engine  is  transmit- 
ted to  the  rear  wheels  electrically  through  a  generator  con- 
nected with  the  engine  and  electric  motors  attached  to  the 
wheels,  the  trucks  of  the  four-wheel  drive  type  having  a  motor 
applied  to  the  front  as  well  as  to  the  rear  wheels.  There  are 
also  several  examples  of  hydraulic  transmission  in  which  the 
power  is  transmitted  to  the  rear  axle  by  engine-driven  pumps 
and  hydraulic  motors.  Friction  drive  is  not  as  frequently  used 
as  the  above  mentioned  types. 

Owing  to  the  great  importance  of  tractive  effort  on  a  large 
truck,  it  is  not  uncommon  to  find  well  developed  examples 
of  four-wheel  drives  -or  "couple  gears,"  in  which  all  wheels  are 
equally  driven.  These  trucks  are  generally  either  of  the  elec- 
tric or  hydraulic  transmission  type  owing  to  the  difficulties 
experienced  in  mechanically  connecting  the  power  with  the 
swiveled  front  wheels.  In  any  case,  the  complication  of  the 
four-wheel  drive  is  so  great  as  to  exclude  it  from  any  but  the 
heaviest  trucks.  Four-wheel  drive  gives  increased  hill  climb- 
ing ability,  stability  on  slippery  pavements,  and  an  increase 
in  towing  power. 

The  greatest  point  of  difference  between  trucks  and  pleas- 
ure cars  generally  lies  in  the  manner  by  which  the  power  is 
transmitted  from  the  transmission  gears  to  the  rear  wheels, 
this  difference  being  particularly  evident  in  the  larger  trucks. 
While  a  bevel  gear  driven,  live  rear  axle  is  used  in  both  pleas- 
ure and  light  delivery  cars,  the  low  speed  of  the  large  rear 
wheels  in  heavy  trucks  together  with  the  great  speed  reduc- 
tion demands  a  different  system.  This  must  be  such  that  the 


46  MOTORS  AND  MECHANISM 

reduction  between  engine  and  road  wheel  speed  is  much 
greater  than  with  the  pleasure  car,  it  must  be  capable  of  with- 
standing the  enormous  shocks  produced  by  driving  over  rough 
roads,  and  must  if  possible  prevent  the  transmission  of  road 
shocks  to  the  delicate  parts  of  the  engine,  gearing  and  axle. 
In  addition,  the  truck  system  must  be  capable  of  withstand- 
ing the  heavy  stresses  due  to  the  increased  torque  and  pull  at 
low  speeds  stresses  that  are  much  heavier  than  those  encoun- 
tered with  the  high  speed  pleasure  car.  It  should  be  noted 
here  that  the  pull  or  twist  on  any  part  increases  in  direct 
proportion  to  the  decrease  in  speed  with  equal  power,  so  that 
with  half  speed  the  stresses  are  twice  as  great  as  those  at  full 
speed  with  equal  transmission  of  power.  This  if  course  neg- 
lects stresses  due  to  vibration  and  windage  that  increases  as 
the  square  of  the  speed. 

As  explained  in  the  first  chapter,  the  rear  axle  of  the  pro- 
peller shaft-driven  car  is  split,  one-half  of  the  shaft  being  con- 
nected to  one  wheel  and  one-half  to  the  other.  One-half  the 
differential  gear  is  connected  to  each  half  shaft,  the  complete 
unit  being  installed  in  the  axle  tube.  This  of  course  produces 
a  weak,  complicated  rear  axle  system  and  necessitates  placing 
the  delicate  differential  gears  where  they  are  subjected  to 
the  full  force  of  the  road  shocks,  a  condition  permissible  on 
light  cars  and  delivery  wagons  but  not  particularly  desirable 
for  heavy  trucks. 

By  using  a  chain  drive  it  is  possible  to  incorporate  the 
differential  in  the  transmission  housing  and  to  place  the  com- 
bined unit  on  the  frame  where  it  is  protected  from  road  shocks 
by  the  intervention  of  the  springs.  This  also  permits  the  use 
of  strong,  solid,  one-piece  rear  axle  of  simple  construction 
with  high  road  clearance.  The  chain  protects  the  engine  and 
drive  mechanism  from  excessive  road  shocks  by  reason  of  its 
flexibility,  that  is,  it  protects  these  parts  from  the  torsional 
shocks  due  to  suddenly  checking  the  rotation  of  the  road 
wheels.  When  protected  from  dirt  by  a  casing,  the  chain 
drive  is  reliable  and  noiseless,  or  at  least  as  noiseless  as  it 
is  necessary  with  a  truck. 


MOTORS  AND  MECHANISM 


47 


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48 


MOTORS  AND  MECHANISM 


Worm  drive  may  either  be  placed  directly  on  the  rear  axle 
in  place  of  the  usual  bevel  shaft  drive  or  may  be  used  in  con- 
nection with  a  chain  drive.  The  worm  gear  is  efficient  and 
is  capable  of  a  great  speed  reduction  without  much  reduction 
in  the  road  clearance.  The  twist  in  the  axle  tube  of  the  worm 
gear  caused  by  the  power  or  by  braking  is  resisted  either  by  a 
torque  tube  or  radius  rod  as  in  the  bevel  driven  axle  or  by  the 


CHASSIS  OF  GASOLINE  TRUCK. 

action  of  the  springs,  an  arrangement  known  as  the  "Hotch- 
kiss"  drive.  By  the  latter  method  the  rear  semi-elliptic  springs 
carry  both  the  weight  of  the  vehicle  and  the  torsion  of  the 
axle.  Both  systems  are  extensively  used  and  at  present  it  is 
difficult  to  say  which  presents  the  most  advantages. 

A  typical  chain  driven  truck  is  shown  by  Fig.  1  in  which 
the  engine  E  is  mounted  in  the  chassis  frame  F,  a  sliding 
transmission  T  being  connected  to  the  engine  through  the 
shaft  M.  A  pinion  J  drives  the  main  bevel  K  in  which  the 
differential  O  is  installed,  a  shaft  Q  running  from  the  differen- 


MOTORS  AND  MECHANISM  49 

tial  to  the  two  chains  P  and  P1.  This  mechanism  is  covered 
by  the  housing  A.  Two  brakes  L  and  L1  are  mounted  on  the 
end  of  the  drive  shaft  Q.  From  the  sprockets  P  and  P1  run 
two  chains  C  and  C1  to  the  main  sprockets  G  and  G1  fastened 
to  the  wheels  W  and  W1.  Brake  drums  are  mounted  on  the 
interior  of  the  sprockets.  The  weight  is  carried  by  the  springs 
H  and  I  at  front  and  rear.  As  both  wheels  turn  freely  on  the 
shaft  it  is  possible  by  this  arrangement  to  have  a  solid  bar 
rear  axle  X.  The  radiator  R  is  in  the  usual  place,  both  the 
engine  and  radiator  being  covered  by  a  hood  or  by  the  foot- 
board, depending  on  the  body  design.  The  pedals  and  brake 
controls  are  the  same  as  on  the  usual  pleasure  car,  that  is 
a  change  gear  lever,  pedal  brake,  emergency  brake  and  throt- 
tle. The  steering  wheel  is  indicated  by  Z. 

Except  on  the  lightest  express  and  delivery  cars,  the  tires 
are  solid  owing  to  the  fact  that  vibration  is  not  of  as  much 
importance  on  the  truck  as  reliability  and  the  ability  to  stand 
up  under  heavy  loads.  Depending  on  the  size  of  the  truck, 
there  may  be  one  or  two  separate  sets  of  solid  tires  mounted 
on  each  wheel. 

Electric  Trucks. 

On  short  hauls  and  under  proper  road  conditions  the  electric 
truck  is  more  economical  than  the  gasolene,  especially  if  the 
loads  are  light  and  if  there  are  many  stops  to  be  made.  For 
long,  fast  hauls  it  cannot  compete  with  the  gasolene  machine. 
Each  has  its  individual  field  of  usefulness. 

Mechanically,  the  electric  truck  proper  is  very  simple,  con- 
sisting as  it  does  of  an  electric  motor,  storage  battery,  reduc- 
tion gear,  and  controller.  Unfortunately  this  is  not  all  of  the 
apparatus  necessary  for  its  operation  since  there  are  a  num- 
ber of  devices  used  in  the  charging  that  do  not  appear  on  the 
car,  soi^  of  which  are  expensive  in  both  first  cost  and  in 
operation.  The  most  expensive  part  of  the  electric,  the  battery, 
deteriorates  rapidly  unless  properly  cared  for,  the  mileage 
per  charge  is  low,  and  the  owner  is  always  at  the  mercy  of 


50  MOTORS  AND  MECHANISM 

the  local  electric  light  -company  unless  he  goes  to  the  further 
expense  of  installing  a  generating  system. 

Except  in  the  arrangement  of  the  gear  used  for  reducing 
the  high  speed  of  the  motor  to  that  of  the  road  wheels  there 
is  not  a  great  diversity  of  design  possible  with  an  electric 
truck.  The  motor  may  be  mounted  on  the  rear  axle  and  drive 
through  planetary  reduction  gears  in  the  wheels,  or  the  motor 
may  drive  through  chains  or  a  worm  as  in  the  case  of  the  gas 
car.  Worm  drive  is  popular  with  electric  pleasure  vehicles, 
while  combinations  of  gears  and  chains  may  be  used  for  the 
trucks.  It  should  be  remembered  that  the  speed  of  an  electric 
motor  is  much  higher  than  that  of  a  gasolene  motor,  and  as  the 
road  speeds  are  generally  lower  with  the  electric  there  is  a  ne- 
cessity of  greater  reduction  in  the  gearing.  In  some  cases,  two 
electric  motors  are  used,  one  for  each  wheel,  so  that  no  differ- 
ential is  required.  To  prevent  a  great  reduction  in  the  final 
drive  it  is  common  practice  to  have  an  intermediate  gear  in 
the  housing  of  the  motor,  on  the  countershaft  principle. 

Either  lead  or  Edison  batteries  may  be  used,  the  former 
being  the  most  efficient  and  generally  the  more  desirable, 
while  the  latter  are  lighter  and  not  as  easily  damaged  by  care- 
less handling  or  neglect.  Often  the  latter  condition  more  than 
overbalances  the  efficiency  of  the  lead  cell,  especially  when 
overhead  is  considered.  The  voltage  of  the  Edison  cell  is 
lower,  and  the  bulk  of  the  cells  for  a  given  voltage  is  greater 
than  the  lead  type,  but  the  total  weight  is  lower,  and  they 
may  be  totally  discharged  without  damage.  Lead  cells  re- 
quire continual  attention  and  cannot  be  left  in  a  discharged 
condition  without  damage,  but  possess  the  ability  to  tempo- 
rarily "come  back"  after  the  discharge  has  been  carried  below 
normal.  The  voltage  fluctuation  is  comparatively  small  be- 
tween full  charge  and  normal  discharge.  The  voltage,  per 
cell,  of  the  lead  battery  is  2.6  volts  at  full  charge  and  that  of 
the  Edison  battery  1.4  approximately,  thus  demanding  more 
Edison  than  lead  batteries  in  series  for  a  given  voltage. 

The  lead  cell  consists  of  two  or  more  plates  immersed  in 
a  dilute  solution  of  sulphuric  acid,  the  surfaces  of  the  plates 


MOTORS  AND  MECHANISM  51 

being  covered  with  a  paste  of  lead  salts  known  as  the  "active 
material."  The  composition  of  the  active  material  on  the 
positive  plate  varies  from  that  on  the  negative  owing  to  the 
action  of  the  charging  current.  The  acid  acting  on  the  active 
material  in  changing  its  chemical  composition  produces  the 
"secondary"  or  discharge  current  of  the  cell.  Current  is 
produced  until  the  material  is  entirely  decomposed  by  the 
acid.  During  the  discharging  process  the  density  of  the  acid 
also  changes,  the  specific  gravity  varying  from  1,300  at  full 
charge  to  1,150  in  the  fully  discharged  condition. 

When  exhausted,  the  cells  are  recharged  by  passing  current 
through  the  plates  and  acid  in  the  opposite  direction  to  that 
produced  during  the  discharge.  This  requires  direct  current 
and  must  be  maintained  at  a  rate  depending  on  the  make  and 
size  of  cell.  It  is  one  of  the  serious  drawbacks  to  the  electric 
vehicle  that  the  charging  process  takes  so  long  a  time,  and 
that  it  must  be  repeated  so  frequently.  Owing  to  the  evapora- 
tion of  the  battery  solution  it  gradually  becomes  more  dense 
so  that  it  must  be  tested  occasionally  and  reduced  if  necessary. 

As  it  is  impossible  to  charge  a  battery  directly  from  an 
alternating  current  main  and  as  the  majority  of  lighting  cir- 
cuits at  the  present  time  deliver  alternating  current,  it  is 
necessary  to  use  a  rectifier  in  such  a  circuit  when  charging. 
A  rectifier  is  an  appliance  used  for  converting  an  alternating 
current  into  direct,  or  for  straightening  out  the  continually 
reversing  alternating  waves  so  that  they  will  flow  through 
the  battery  in  constant  direction.  Another  device  known  as 
a  "converter"  -performs  the  same  function,  and  is  used  prin- 
cipally in  cases  where  a  number  of  vehicles  are  to  be  charged 
at  the  same  time.  When  direct  current  is  furnished  by  the 
electric  light  mains  it  is  only  necessary  to  install  a  rheostat 
for  the  control  of  current  strength. 

»  > 

The  Electric  Motor. 

The  motor  used  with  the  electric  truck  is  of  what  is  known 
as  the  series  type  in  which  the  field  circuit  and  armature  are 


52  MOTORS  AND  MECHANISM 

connected  in  series.  This  gives  the  most  powerful  pull  or 
starting  torque  and  is  of  the  type  generally  used  in  electric 
street  cars,  although  much  smaller. 

The  Control  System. 

In  regard  to  control,  the  electric  truck  is  much  simpler  to 
handle  and  gives  a  wider  variation  of  speeds  by  a  single  lever 
than  the  gasolene  machine,  there  being  but  a  single  control 
lever  and  a,  brake.  The  control  lever  corresponds  roughly  to 
the  control  lever  on  an  electric,  street  car,  Inasmuch  as  its 
action  is  to  control  the  flow  of  the  current  through  the  motor. 
It  varies  the  voltage  at  the  motor  from  a  few  volts  to  the  full 
voltage  of  the  battery,  usually  from  60  to  80  volts  and  as  the 
speed  of  the  motor  is  roughly  proportional  to  the  voltage, 
other  conditions  being  equal,  it  therefore  varies  the  speed. 
When  on  a  hill  or  incline,  the  increase  of  speed  due  to  a  given 
vjoltage  is  not  as  great  as  when  on  the  level  owing  to  the  fact 
that  the  motor  must  be  slowed  down  to  allow  more  current 
to  flow  and  thus  meet  the  demands  for  the  increased  power 
necessary  for  climbing  the  hill. 

The  voltage  variation  is  met  in  two  of  three  possible  com- 
binations, or  in  the  case  with  two  motors  is  accomplished  by 
all  three.  The  first  and  a  seldom  used  method  is  by  using  a 
variable  amount  of  resistance  in  series  with  the  motor  and 
battery,  the  amount  of  resistance  being  determined  by  the 
position  of  the  controller  handle,  all  batteries  being  at  all 
times  in  circuit.  This  method  is  very  wasteful,  since  the 
energy  due  to  the  drop  in  voltage  is  all  converted  into  useless 
heat. 

A  second  method  used  in  all  single  motor  vehicles  is  known 
as  the  "Series-Parallel"  control  in  which  very  little  resistance 
is  used,  and  this  only  on  intermediate  control  steps.  By  this 
method  the  battery  arrangement  is  varied  by  the  controller  so 
that  more  or  less  cells  are  connected  in  series,  thus  varying 


MOTORS  AND  MECHANISM 


53 


A— Ignition  Cable  Support 

B — Carbureter 

C — Exhaust  Camshaft 

C1— Intake  Camshaft 

D — Supporting  Arms 

E — Exhaust  Manifold 

F— Fly-Wheel  (Rear) 

G— Lower  Half  of  Crank-Case 

H—  Water  Manifold 

I— Gas  Intake  Manifold 


T — Silent  Chain  Magneto  Drive 

K— Piston 

L — Spark  Plug 

M — Magneto 

MS— Valve  Plug 

N — Combustion   Chamber 

P — Water  Pump 

Q— Throttle 

R — Water  to  Radiator 

S— Fan  Front 


54  MOTORS  AND  MECHANISM 

the  voltage  at  the  motor.  As  the  steps  between  the  different 
possible  combinations  of  cells  would  differ  too  greatly  in  volt- 
age, a  very  small  resistance  is  introduced  in  the  intermediate 
steps  so  that  the  truck  will  build  up  speed  smoothly  instead 
of  by  a  series  of  jerks.  For  illustration,  but  not  as  an  example 
of  any  particular  case,  we  will  assume  that  our  battery  voltage 
is  60  with  all  30  cells  in  series  for  top  speed,  and  that  the 
voltage  of  each  individual  cell  is  2  volts.  The  arrangement 
of  the  steps  may  be  as  follows,  each  step  being  represented  by 
a  distinct  controller  position : 

Step  1 — First  Speed — Required  10  Volts  at  Motor.  This  will 
call  for  5  cells  in  series  (2  volts  per  cell).  As  we  must  have 
30  cells  for  our  maximum  of  60  volts,  we  will  connect  with 
the  controller  so  that  there  will  be  6  sets  in  multiple,  thus 
giving  a  series-multiple  combination.  As  a  multiple  com- 
bination gives  a  greater  volume  of  current  than  if  we  used 
a  single  set  of  5  cells,  we  have  met  our  starting  condition. 
Step  2 — Second  Speed — Required  18  Volts  at  Motor.  This 
voltage  cannot  be  met  exactly  by  any  one  combination  of 
30  cells,  since  we  will  require  9  cells  in  series  and  this  is 
not  contained  equally  into  30  for  the  multiple  connection. 
We  will  therefore  be  compelled  to  adopt  the  next  higher 
equal  combination  and  cut  down  the  higher  voltage  obtained 
by  a  resistance.  Ten  cells  in  series  will  give  20  volts,  and  as 
10  is  contained  into  30  three  times,  we  will  have  3  groups 
of  10  cells  in  series.  The  difference  between  20  and  18  volts 
must  be  cut  down  by  resistance.  As  even  this  small  re- 
sistance is  wasteful  we  must  endeavor  not  to  run  for  any 
length  of  time  on  Step  2. 

Step  3— Third  Speed— Required  24  Volts  at  Motor.  This 
will  require  12  cells  in  series,  but  this  is  also  impossible  as 
a  direct  speed  as  12  is  not  contained  equally  into  30.  We 
must  take  the  next  higher  combination  with  resistance  as 
before.  At  30  volts  we  will  require  15  cells,  in  series  with 
enough  resistance  to  cut  this  down  to  24  volts. 


MOTORS  AND  MECHANISM  55 

Step  4— Fourth  Speed—Required  30  Volts  at  Motor.  This  is 
an  even  speed,  as  with  30  volts  we  will  need  15  cells,  and 
15  is  contained  equally  in  30.  As  we  already  have  15  cells 
in  series  it  will  only  be  necessary  for  the  controller  to  cut 
out  the  resistance  without  changing  the  cell  connections. 
Step  5— Fifth  Speed— Required  36  Volts  at  Motor.  This  will 
require  resistance.  Remaining  intermediate  steps  as  before 
— using  resistance,  etc. 

Top  Speed — Required  60  Volts  at  Motor.     All  cells  are  in 
series  with  full  battery  voltage  at  60  volts. 
The  motor  voltages  specified  above  are  those  supposed  to 
be  found  necessary  for  a  uniform  increase  in  the  speed.    These 
are  generally  first  determined  by  experiment  with  a  given 
type  of  truck  for  the  reason  that  the  road  resistance,  etc.,  of 
every  truck  type  varies  throughout  the  speed  range  at  a  dif- 
ferent rate.    Because  of  the  waste  energy,  continuous  running 
should  not  be  done  on  the  resistance  speeds. 

In  running,  the  brake  should  not  be  applied  until  the  con- 
troller is  in  the  off  position  and  with  the  motor  completely  out 
of  circuit,  for  this  would  produce  a  heavy  and  injurious  draft 
of  current  from  the  battery.  Many  controllers  are  interlocked 
with  the  brake  system  in  such  a  way  that  either  the  move- 
ment of  the  brake  lever  will  open  the  motor  circuit,  or  the 
brake  system  will  be  operated  directly  by  the  controller  lever 
itself. 

A  voltmeter  and  ammeter,  and  sometimes  a  wattmeter,  are 
placed  on  the  dash  so  that  the  condition  of  the  batteries  and 
amount  of  current  drawn  can  be  readily  determined.  The 
wattmeter  measures  the  total  amount  of  power  consumed  or 
supplied  to  the  vehicle  (watts  =  volts  X  amperes),  so  that  the 
owner  can  compute  the  cost  per  ton  mile  of  the  goods  deliv- 
ered. The  tonnage  is  of  course  determined  by  the  scale-yard 
while  the  mileage  is  determined  by  the  speedometer,  and  by 
properly  kept  records  of  these  quantities  it  is  possible  to  regu- 
late the  traffic  so  that  the  expenses  can  be  kept  at  the  lowest 
point. 


56  MOTORS  AND  MECHANISM 

Truck  Governors. 

At  the  present  time  nearly  every  gasolene  truck  is  provided 
with  some  form  of  governing  device  lor  keeping  the  speed  of 
the  machine  under  certain  limits.  This  device  is  installed  to 
prevent  overspeeding  and  misuse  by  the  drivers  and  for  this 
reason  is  an  important  factor  in  prolonging  the  life  of  the  car. 
In  some  -localities  there  are  ordinances,  that  have  been  passed 
or  are  under  consideration,  that  require  a  governor  on  every 
commercial  vehicle. 

So  destructive  are  the  results  of  overspeeding  a  heavy  truck 
that  many  truck  builders,  who  are  bound  under  a  guarantee 
contract,  send  inspectors  periodically  to  determine  whether 
there  has  been  any  tampering  with  the  governor  adjustment 
due  to  the  customers'  desire  for  "speeded  up"  service. 

Aside  from  the  question  of  abuse,  a  governor  has  a  decided 
effect  In  increasing  the  efficiency  of  motor  operation.  Since 
automatic  throttle  control  is  not  affected  to  such  a  degree  by 
the  jolts  and  jars  to  which  a  commercial  vehicle  is  subjected, 
the  gas  flow  to  the  engine  is  more  uniform  and  the  carburetor  is 
correspondingly  more  efficient.  In  addition,  the  governor  will 
hold  the  engine  at  the  most  efficient  speed  which  is  seldom 
attained  through  any  considerable  period  by  manual  control. 

In  general  the  governors  now  used  can  be  divided  into  three 
principal  classes,  according  to  their  method  of  control:  (1) 
Governors  controlling  by  centrifugal  force ;  (2)  governors  actu- 
ated by  hydraulic  pressure. 

Hydraulic  governors  regulate  through  the  variation  in  pres- 
sure of  the  water  in  the  cooling  system,  the  water  acting  usu- 
ally on  a  flexible  leather  diaphragm,,  the  action  of  which  is 
transmitted  to  a  regulating  gas  valve  through  a  linkage  or  lever 
system.  Since  the  pressure  of  the  water  on  the  diaphragm  is 
directly  proportional  to  the  engine  speed,  there  is  a  definite  gas 
valve  opening  for  every  engine  speed,  the  gas  admission  being 
independent  of  the  load  on  the  engine.  This  is  the  type  used 
by  the  Packard  truck. 

The  greater  majority  of  governors  act  by  utilizing  the  cen- 


MOTORS  AND  MECHANISM 


57 


trifugal  force  developed  by  revolving  pivoted  weights,  the 
weights  either  operating  a  gas  valve  or  acting  on  the  ignition 
system  in  a  manner  similar  to  the  governor  of  a  steam  engine. 
In  effect  the  governor  consists  of  a  vertical  rotating  shaft  on 
which  is  mounted  a  pair  of  pivoted  weights  controlled  by 
springs  which  pull  them  towards  the  shaft.  As  the  speed  of 
the  shaft  increases,  the  centrifugal  force  acting  on  the  weights 
tends  to  pull  them  outward  against  the  pull  of  the  springs.  In 
moving  out,  the  weights  through  a  lever  system  raise  a  collar 


TRUCK  GOVERNORS. 
Centrifugal   Type   Governor  at   Left — Hydraulic   Governor  at  Right. 

which  in  turn  closes  a  gas  valve,  cuts  out  the  ignition,  or 
advances  and  retards  the  spark. 

Driven  from  the  engine,  the  governor  tends  to  keep  a  con- 
stant engine  speed  independent  of  the  speed  of  the  vehicle 
when  on  different  positions  of  the  change  gears.  With  con- 
stant engine  speed,  the  only  variation  in  the  vehicle  spe'ed  is 
made  by  the  different  gear  combinations  in  the  transmission. 

When  driven  from  the  vehicle  wheels  or  from  the  propeller 
shaft,  the  governor  still  acts  on  the  gas  valve  or  ignition  sys- 


58  MOTORS  AND  MECHANISM 

tern  but  allows  the  engine  speed  to  vary  with  the  gear  ratios 
in  the  transmission,  the  limit  being  only  on  the  speed  of  the 
road  wheels. 

In  either  case,  control  by  a  gas  valve  situated  between  the 
carburetor  and  engine  is  far  superior  to  control  by  advance 
or  retard  or  by  ignition  cut-out. 

Speed  Control. 

When  the  governor  is  driven  directly  either  by  centrifu- 
gal force  or  by  hydraulic  pressure  and  acts  on  a  gas  valve 
reducing  the  flow  of  the  mixture  when  the  engine  exceeds  a 
certain  speed  there  is  no  power  advantage  in  dropping  into 
the  low  gear  except  for  that  due  to  the  increased  leverage  of 
the  reduction  gearing.  Since  the  engine  cannot  be  speeded 
up  beyond  a  certain  speed  on  low  the  tractive  effort  is  lim- 
ited within  a  short  range. 

With  a  low  maximum  engine  speed  the  life  of  the  engine  is 
increased  but  at  the  expense  of  the  power  developed  by  a 
certain  size  engine,  thus  a  compromise  must  be  made  between 
the  output  and  the  life  of  the  motor.  To  operate  the  motor 
at  a  low  speed  on  high  gear  it  is  necessary  to  sacrifice  power 
on  the  low  gears  at  the  very  time  when  the  greatest  power  is 
required.  'This  often  results  in  running  an  engine  at  a  speed 
50  per  cent  less  than  would  have  been  possible  on  low  speed. 

According  to  Theodore  Douglas  in  a  paper  read  before  the 
Society  of  Automobile  Engineers,  a  truck  only  utilizes  30  per 
cent  of  the  rated  power  output  during  90  per  cent  of  the  run- 
ning time.  This  means  that  the  motor  is  throttled  down  to 
an  inefficient  point  at  practically  all  times  in  its  travels,  and  it 
would  seem  offhand  that  it  would  be  the  best  practice  to  have 
the  gear  ratio  such  that  the  engine  speed  would  be  reduced 
to  a  point  more  closely  corresponding  to  the  actual  power 
required,  running  on  full  throttle,  or  else  decrease  the  size  of 
the  motor. 


MOTORS  AND  MECHANISM 
Speed. 


59 


With  the  governor  attached  to  the  vehicle  wheels,  or  what 
is  the  same  thing,  attached  to  the  propeller  shaft,  the  engine 
speed  limit  varies  according  to  the  particular  transmission 
gear  that  is  in  .mesh  at  any  one  time.  This  allows  operation 
on  high  gear  with  moderate  engine  speeds.  As  the  car  is 
thrown  into  the  lower  gears,  the  engine  speed  increases  to 
maintain  the  limit  of  vehicle  speed  thus  increasing  the  pull 
on  low  as  it  should  be,  but  may  allow  the  motor  to  race  at 


GOVERNOR  CONTROLLED  FROM  PROPELLER  SHAFT. 

an  excessive  speed  on  second  gear  and  to  a  prohibitive  speed 
on  first  and  when  standing  still  in  neutral.  When  standing 
still,  there  is  of  course  no  limit  to  the  engine  speed  with  this 
type  of  governor. 

In  the  following  Mr.  Douglas  summarizes  the  character- 
istics of  an  ideal  vehicle  governor: 

Power — This  is  the  most  important  quality  of  a  governor, 
and  upon  it,  and  its  proper  balance,  will  depend  very  largely 
its  efficiency.  To  possess  this  quality  effectively  the  governor 
must  be  static,  that  is,  be  a  one-speed,  one-position  governor. 

Sensitiveness — This  quality  is  dependent  on  a  positive  in- 
crease and  decrease  in  power  between  small  variations  of 


6o 


MOTORS  AND  MECHANISM 


position,  and  hence  of  speed,  and  the  difference  in  speed  be- 
tween any  two  positions  must  be  small. 

Flexibility — The  governor  should  be  capable  of  maintain- 
ing the  power  output  of  the  engine  closely  proportionate  to 
the  power  requirement,  regulating  to  slow  engine  speeds  for 
high  gear  service,  where  low  power  is  required,  and  to  higher 
engine  speed  for  low  gears  when  the  maximum  power  capacity 
of  the  engine  can  be  effectively  employed. 

Delivery — This  quality  is  dependent  largely  on  the  type  of 
control  valve  employed.  The  governor  construction  should  be 
such  as  to  include,  and  to  co-ordinate  with,  a  valve  of  such 
design  as  to  require  but  slight  travel  in  effecting  its  extremes 
of  position.  The  valve  should  be  non-fluttering,  of  low  resist- 
ance to  the  gas  flow,  and  offer,  in  the  automatic  control  of  the 
engine,  full  throttle,  when  necessary,  until  practically  the  mo- 
ment of  required  cutoff  is  reached. 

Regularity — The  governing  influence,  power  and  valve 
closure  should  vary  proportionately  as  the  speed ;  or,  between 
the  extremes  of  the  governor  range  the  differences  in  power 
and  closure  between  any  two  required  intermediate  positions, 
should  be  equal. 


GOVERNOR  DRIVEN  FROM  ROAD  WHEELS. 


MOTORS  AND  MECHANISM  61 


CHAPTER  V 
CONE  AND   DISC  CLUTCHES 

As  explained  in  Chapter  I,  the  clutch  is  for  the  purpose  of 
disconnecting  the  engine  from  the  driving  gear  of  the  car, 
this  being  necessary  when  changing  gear,  reversing  the  car, 
or  in  making  short  stops  with  the  engine  running.  These 
clutches  are  invariably  of  the  friction  type  in  which  the  driving 
force  is  transmitted  through  the  friction  between  two  abutting 
surfaces. 

While  many  types  of  friction  clutches  have  been  devised 
from  time  to  time,  nearly  every  car  in  the  market  is  supplied 
with  one  of  two  types — either  the  cone  or  the  disc  clutch. 
The  frictional  surfaces  may  be  either  metal  to  metal,  or  metal 
to  leather  or  fabric,  the  majority  of  cone  clutches  being  of  the 
latter  class. 

A  typical  cone  clutch  is  shown  by  Fig.  1,  in  which  F  is  the 
fly-wheel  and  C  is  part  of  the  engine  crank-shaft,  the  fly-wheel 
being  attached  to  the  crank-shaft  by  the  bolted  flange  T. 
The  interior  of  the  fly-wheel  is  bored  out  with  a  taper  face 
shown  by  B,  which  forms  the  frictional  surface  of  the  engine 
half  of  the  clutch.  A  prolonged  portion  of  the  crank-shaft  E 
serves  to  support  and  center  the  other  half  of  the  clutch.  A 
cone  A,  the  driven  member  of  the  clutch,  has  a  leather  covered 
face  D  turned  to  the  same  t^per  as  the  fly-wheel  face  B. 
When  the  cone  is  forced  to  the  right  by  the  spring  I  the  faces 


62 


MOTORS  AND  MECHANISM 


TYPICAL  CONE  CLUTCHES. 

Fig.  1. — Simple  Type  of  Cone  Clutch. 
Fig.  2.— Cone  Reversed  with  Thrust  Bearing. 

Figs.  3,  4. — Cone  Clutch  Arranged  So  That  There  is  No   End  Thrust. 
Fig.  5. — Spring    I    Under    Leather    E    Allows    Easy   and    Gradual    Engagement   with 

Face  B  of  the  Fly-Wheel  F.     D  is  the  Clutch  Leather. 

Fig.   6. — The   Cork   E   Causes   Easy   Engagement  with   Fly-Wheel    Face   B.     Leather 
D    Comes    Into    Engagement   After   Cork   is    Fully    Compressed. 


MOTORS  AND  MECHANISM  63 

B  and  D  engage  so  that  the  engine  drives  the  propeller  shaft 
N.  The  driving  force  is  due  to  the  frictional  engagement 
between  B  and  D,  and  as  the  friction  is  proportional  to  the 
pressure  of  D  on  B,  the  drive  is  assisted  by  the  wedging  of 
the  taper  cone  in  the  bore.  The  smaller  this  angle  of  taper, 
the  greater  will  be  the  pressure  between  the  two  parts.  If 
this  angle  is  made  too  small,  the  clutch  will  be  difficult  to 
release  and  is  likely  to  be  "Savage"  or  "Fierce,"  that  is,  will 
take  hold  with  a  sudden  jerk.  In  practice,  with  a  leather  faced 
cone,  this  angle  is  generally  about  12  degrees. 

The  inner  end  of  the  cone  hub  G,  turns  freely  on  the  shaft 
extension  E  which  tends  to  center  it  in  the  bore  and  supports 
the  long  overhang  of  the  shaft  N.  The  spring  I  acts  against 
the  hub  at  the  left  and  a  shaft  collar  K  at  the  right.  When 
the  clutch  pedal  P  is  depressed  in  the  direction  of  the  arrow 
L,  the  slotted  end  M  of  the  pedal  lever  acts  on  the  collar  H, 
causing  the  cone  to  be  disengaged  by  moving  to  the  right. 
The  pedal  lever  O  turns  on  the  spindle  J,  and  the  cone  hub  G 
is  keyed  to  the  shaft  N  which  leads  to  the  transmission  and 
from  there  to  the  propeller  shaft. 

Since  the  amount  of  friction  between  B  and  D  limits  the 
driving  power  of  the  clutch  we  must  not  only  obtain  great 
pressure  from  the  spring  and  wedge  combination  but  we  must 
select  those  materials  for  the  faces  that  produce  the  greatest 
friction.  Since  leather  on  iron  has  a  high  friction  coefficient, 
it  is  usual  to  make  F  of  cast  iron  and  D  of  leather.  A  metal 
to  metal  contact  would  slip  too  much  with  equal  spring  pres- 
sure, especially  if  greasy.  The  pliability  of  the  leather  helps  in 
making  the  engagement  soft  and  steady,  and  for  the  best 
results  the  leather  must  be  kept  soft  by  occasional  treatments 
of  neatsfoot  or  castor  oil.  A  dry,  hard,  burned  leather  makes 
a  fierce,  quick  grabbing  clutch  that  not  only  is  uncomfortable 
to  the  occupants  of  the  car  but  that  also  unnecessarily  strains 
the  driving  mechanism. 

To  prevent  grabbing  it  is  now  the  practice  to  .place  small 
springs  or  rubber  under  loosened  parts  of  the  leather  facing  so 
that  the  leather  over  the  springs  is  raised  above  the  general 


64  MOTORS  AND  MECHANISM 

surface  of  the  cone.  As  the  high  spots  first  come  into  engage- 
ment, and  then  are  gradually  forced  down  until  the  whole 
surface  is  engaged,  the  car  picks  up  speed  very  softly  and 
easily.  Small  corks  inserted  in  the  cone  serve  the  same  pur- 
pose, the  corks  being  allowed  to  project  above  the  cone  when 
disengaged. 

The  cone,  and  all  parts  connected  with  the  driving  mechan- 
ism to  the  right  of  the  fly-wheel,  must  be  light  and  have  as 
little  momentum  as  possible  so  that  the  cone  will  not  spin  long 
after  being  released  from  the  fly-wheel  member.  If  the  cone 
spins  fast  or  long  after  the  release  it  will  be  difficult  to  shift 
the  transmission  gears  and  to  get  the  teeth  to  mesh.  Spinning 
accounts  to  a  great  degree  for  the  noise  made  in  changing 
gears.  To  reduce  the  momentum,  the  cone  base  is  usually 
made  of  aluminum  or  light  sheet  steel,  and  in  many  instances 
is  provided  with  a  braking  device  that  checks  the  speed  of  the 
cone.  The  brake  comes  into  action  only  when  the  cone  is 
released. 

As  the  spring  shown  must  necessarily  be  very  stiff  to  get 
the  proper  pressure  on  the  cone,  it  exerts  considerable  end 
thrust  on  the  bearings,  and  therefore,  causes  wear.  This  has 
been  disposed  of  variously  in  the  practical  clutches  by  ball 
bearing  thrusts  or  by  rearrangement  of  the  parts  so  that  little 
trouble  is  experienced  from  this  source  in  modern  cars.  It 
should  be  understood  that  the  clutch  in  Fig.  1  is  merely 
diagrammatic,  and  is  only  intended  to  show  the  elementary 
principles  of  the  cone.  Practical  examples  will  follow. 
,  Fig.  2  .is  a  cone  clutch  in  which  the  taper  of  the  cone  is 
reversed,  the  cone  no  longer  engaging  with  the  fly-wheel  but 
with  the  female  member  R,  which  is  bolted  to  the  wheel  F. 
The  cone  A,  which  is  inside  the  assembly,  has  its  leather  fac- 
ing D  brought  into  contact  with  R  by  the  internal  spring  I. 
This  spring,  which  acts  against  the  wheel  flange  at  K,  and 
the  cone  ball  bearing  thrust  S,  forces  the  cone  to  the  right. 
The  ball  thrust  bearing  S  reduces  the  twisting  on  the  spring 
when  the  engine  is  running  with  the  clutch  disengaged.  It 
will  be  noted  that  with  this  arrangement  there  is  no  end 


MOTORS  AND  MECHANISM  65 

thrust  brought  on  rotating  bearings  when  the  clutch  is  en- 
gaged, and  that  the  friction  surfaces  are  protected  against 
the  entrance  of  dirt. 

An  external  extension,  B,  of  the  hub  at  the  right  carries 
the  shift  collar  H,  which  is  actuated  by  the  pedal  fork  M  in  the 
usual  way.  The  pedal  lever  O  is  pivoted  on  the  spindle  J 
which  is  below  the  shaft  N.  This  position  of  the  spindle 
reverses  the  direction  of  cone  movement  from  that  shown  in 
Fig.  1.  C  is  the  crank-shaft,  P  is  the  pedal,  and  N  is  the  shaft 
leading  to  the  transmission,  and  hence  to  propeller  shaft. 
Pedal  movement  is  in  the  direction  L. 

A  cone  clutch  in  which  bearing  end  thrust  is  eliminated  is 
shown  by  Fig.  3,  this  being  a  late  model  built  by  the  Warner 
Gear  Company.  Fig.  4  is  another  example  of  this  type. 

Two  methods  of  procuring  a  gradual  engagement  of  the 
clutch  leather  by  means  of  small  special  springs  or  corks  are 
shown  respectively  by  Figs.  5  and  6. 

Care  of  Lubricated  Disc  Clutches. 

Probably  the  greatest  source  of  trouble  with  a  lubricated 
type  disc  clutch  is  in  the  selection  and  maintenance  of  the  oil. 
Heavy  oils  are  sure  to  cause  trouble  by  causing  the  clutch  to 
slip  excessively  when  first  thrown  in,  and  by  causing  the  discs 
to  drag  when  the  clutch  is  supposed  to  be  out.  A  heavy 
bodied  oil  through  its  viscosity  prevents  the  plates  from  com- 
ing into  contact  immediately  as  it  will  require  a  certain  length 
of  time  for  the  spring  to  squeeze  out  the  oil.  When  the  plates' 
are  disengaged,  the  high  viscosity  will  create  a  heavy  frictional 
drag  between  the  two  sets  of  plates  causing  the  gears  to  spin 
when  shifting  and  making  the  shift  extremely  difficult.  Both 
effects  are  intensified  by  cold  weather,  since  a  low  temperature 
increases  Ae  density  of  the  oil.  It  needs  intelligence  and  care 
to  insure  that  the  oil  is  in  the  proper  condition. 

Owing  to  the  light  pedal  pressure  required  to  operate  this 
type  of  clutch  many  owners  suspect  the  clutch  to  be  slipping 
when  it  is  not,  and  under  this  impression  they  tighten  up  the 
springs  until  the  pressure  is  destructively  heavy.  With  an 


66 


MOTORS  AND  MECHANISM 


TYPICAL  DRY  DISC  CLUTCHES. 


MOTORS  AND  MECHANISM  67 

excessive  spring  pressure  worn  plates  are  the  inevitable  result. 
When  once  worn,  the  space  between  the  plates  increases 
rapidly  and  the  clutch  begins  to  slip.  If  not  regularly  cleaned 
out,  the  oil  bath  becomes  a  carrier  for  the  particles  torn  off  the 
plates  so  that  the  wear  is  again  increased  over  normal.  Make 
a  practice  of  removing  the  old  oil  at  regular  intervals  through 
the  drain,  washing  out  .thoroughly  with  kerosene,  and  filling 
with  new  clean  oil.  If  badly  worn,  more  plates  may  be  added, 
or  if  cork  inserts  are  used  they  may  have  to  be  replaced  by 
new. 

When  no  change  of  lubricant  or  outside  adjustment  will  stop 
the  slipping  of  the  clutch,  or  when  it  is  definitely  known 
through  some  other  source  that  the  parts  are  worn,  it  will  be 
necessary  to  take  down  the  clutch  for  examination  and  repair. 
In  dissembling  particular  attention  should  be  paid  to  the 
powerful  spring  so  that  it  will  not  unexpectedly  jump  out  of 
place  and  injure  the  parts  of  the  clutch  or  the  operator. 

Each  plate  should  be  examined  separately  for  rough  working 
surfaces  and  buckled  faces.  A  slight  roughness  on  one  plate 
may  soon  show  up  and  destroy  the  plate  with  which  it  engages. 
Should  the  roughness  be  very  marked,  the  plate  must  either  be 
reground  or  replaced  with  new,  it  often  being  necessary  to 
replace  six  or  more  plates  in  a  single  clutch.  Buckled  plates 
are  generally  caused  by  the  heat  due  to  insufficient  lubrication, 
and  are  causes  of  erratic  clutch  action.  The  buckles  can  often 
be  removed  and  the  plates  straightened  by  the  careful  use  of  a 
hammer  and  a  block  of  wood  with  the  plate  laid  on  a  perfectly 
level  surface  such  as  a  machinist's  surface  plate. 

Should  the  plates  be  worn  very  thin  it  is  usually  safer  to 
replace  them  with  new  than  by  adding  additional  plates  to  the 
series.  Plates  are  comparatively  cheap  and  it  is  usually  more 
economical  to  replace  suspicious  parts  than  to  run  the  chances 
of  being  compelled  to  dissemble  the  parts  a  second  time. 

In  installing  the  new  plates  see  that  they  fit  accurately  in 
the  grooves  of  the  casing  as  well  as  in  the  grooves  of  the  shaft 
drum  and  that  they  will  move  freely  back  and  forth  laterally. 
If  tight  they  should  be  eased  off  by  a  file,  taking  care  that  the 


68  MOTORS  AND  MECHANISM 

filed  surfaces  are  at  right  angles  to  the  face  of  the  plates  and 
that  no  burrs  or  fins  are  left.  Also  see  that  the  new  plates  do 
not  occupy  more  space  than  the  old  plates  when  they  were 
originally  fitted.  This  can  be  tested  for  by  fitting  up  the 
clutch  temporarily,  without  installing  the  spring  and  noting 
whether  the  lateral  movement  on  the  clutch  shaft  drum  al- 
lowed by  the  clutch  pedal  is  sufficient  to  allow  the  faces  of 
the  discs  to  clear  and  slip  when  the  clutch  is  fully  depressed. 
With  the  spring  in  position  it  is  difficult  to  make  this  test. 

Now  examine  the  inner  ball  bearings  for  wear,  and  if  slack 
exists  they  should  be  replaced  by  new.  While  misalignment 
is  not  of  as  much  importance  in  disc  clutches  as  in  other  types 
it  does  not  improve  their  working,  and  in  many  cases  the  mis- 
alignment, due  to  worn  bearings,  has  been  instrumental  in 
causing  fierce  engagement  and  erratic  slipping.  Again,  worn 
bearings  have  a  tendency  to  throw  stresses  into  the  transmis- 
sion, causing  the  gears  to  run  out  of  mesh  and  run  noisily. 

The  plate  separators  separate  the  plates  when  the  pedal  is 
depressed  so  that  the  driving  and  driven  plates  slip  in  relation 
to  one  another.  See  that  none  of  the  separators  are  missing, 
for  a  missing  spring  or  stud  will  cause  the  plates  to  drag  the 
change  gears  with  the  clutch  released,  and  will  cause  trouble 
in  meshing  the  gears.  Often  these  separator  springs  and 
studs  will  drop  into  inaccessible  parts  of  the  casing  or  will  be 
thrown  out  with  the  old  lubricant.  Search  carefully  through 
the  old  oil  for  any  such  small  parts  before  throwing  it  away. 

In  replacing  the  parts  the  spring  will  probably  be  more 
difficult  to  place  in  the  assembly  than  any  of  the  other  parts 
owing  to  its  stiffness  and  location.  A  long  tube  can  be  slipped 
over  the  projecting  end  of  the  shaft  with  a  drilled  plate  at  the 
end  of  the  tube.  A  long  bolt  (say  one  inch  in  diameter)  is 
inserted  into  a  free  hole  in  the  plate,  with  the  head  resting 
against  a  chassis  cross-member.  A  nut  on  the  bolt  presses 
against  the  out  face  of  the  plate  so  that  the  spring  can  be 
compressed  by  unscrewing  the  nut  against  the  plate.  When 
compressed  the  clutch  cover  can  be  bolted  to  the  housing- 
flange. 


MOTORS  AND  MECHANISM  69 

A  New  Leather  for  the  Clutch. 

Owing  to  the  shape  of  the  surface  of  a  cone  clutch  it  is  not 
an  easy  task  to  cut  a  new  leather  to  fit  the  cone  properly.  In 
the  first  instance  take  off  the  old  worn  leather  surface  and 
rivets  and  be  sure  to  clean  out  the  rivet  holes  thoroughly. 
Now  that  this  is  accomplished,  measure  the  cone,  first  taking 
the  diameters  of  the  small  end,  A,  and  large  end,  B,  then  find 
the  width,  C.  D  represents  the  projection  of  the  cone  in  a  flat 
plane.  Draw  the  line  1  and  2,  then  draw  the  center  line  3  and  4, 


CUTTING  NEW  CLUTCH  LEATHER. 

at  right  angles  to  1  and  2.  Now  prolong  the  two  tapered 
lines,  1  to  5,  2  and  6,  until  they  meet  the  center  line  as  at  7. 
The  point  7  represents  the  apex  of  the  cone,  if  it  were  com- 
pleted, and  gives  the  correct  projection  of  the  development  of 
that  portion  of  the  conical  surface.  With  7  and  1,  7  and  5 
as  radius,  draw  the  two  circles  8,  9,  10,  11.  Also  draw  radial 
lines  12  and  13  to  pass  through  7.  The  figure  in  solid  lines,  E, 
can  then  be  cut  out  of  the  paper  used  for  the  pattern  and 
placed  on  the  leather.  Now  use  the  shears  and  cut  close  to  the 
edge  of  the  pattern,  E,  and  the  proper  cover  has  been  made. 


70  MOTORS  AND  MECHANISM 

Before  putting  it  on  the  cone  soak  the  leather  good  in  oil. 
In  putting  it  on  the  cone,  rivet  the  one  end  first,  next  the 
leather  is  drawn  down  past  the  next  rivet  holes,  which  are 
then  driven  into  place.  NThis  is  continued  until  the  other  end 
of  the  leather  is  reached.  Before  using  the  clutch  let  the 
leather  dry  gradually  and  this  will  give  a  tight  fit. 

Clutches. 

The  gradual  engagement  of  the  Flanders  20  car  is  secured 
by  a  piece  of  rubber  tubing  run  around  the  clutch  cone  and 
under  the  leather.  This  rubber  tube  takes  the  place  of  the 
corks  and  springs  used  in  the  usual  type  of  cone  clutch.  The 
ends  of  the  tube  are  held  by  being  passed  through  the  holes 
where  they  can  be  seen  between  the  arms  of  the  clutch  spider. 

When  the  rubber  has  lost  is  elasticity,  the  clutch  may  grab 
suddenly,  since  the  hardened  rubber  acts  like  the  leather.  To 
fix  it,  the  clutch  facing  must  be  removed  and  a  new  tube  in- 
serted. The  facing  can  be  used  again,  but  as  it  is  likely  to  be 
well  worn  it  will  save  a  second  overhauling  if  it  is  replaced 
by  new. 


SHOWING  DISC  CLUTCH  DISSEMBLED. 


MOTORS  AND  MECHANISM  71 


CHAPTER  VI 
TRANSMISSIONS  OR  "CHANGE  GEARS" 

In  general,  "change  gears"  or  transmissions  can  be  divided  into 
two  principal  classes :  ( i )  The  planetary  type  in  which  the  gears 
are  always  in  mesh.  (2)  The  sliding  gear  type  in  which  the 
speed  changes  are  effected  by  meshing  different  combinations  of 
gears  for  each  speed. 

Both  types  are  widely  used,  the  planetary  gear  in  the  Ford  cars 
and  some  makes  of  light  trucks,  while  the  sliding  gear  type  is 
used  in  the  larger  cars  and  trucks.  The  selective  type  of  sliding 
gear  transmission  is  used  almost  exclusively  at  the  present  time. 

The  following  shows  a  modern  selective  type  change  gear, 
with  appended  diagrams  showing  the  position  of  the  gears  at 
different  speeds.  This  particular  construction  gives  three  for- 
ward speeds  and  one  reverse,  the  third  speed  or  "high"  gear  being 
a  direct  drive  at  engine  speed  to  the  rear  axle  through  the  pro- 
peller shaft. 

The  actual  construction  shown  by  the  longitudinal  section 
is  part  of  a  unit  power  plant  installation  in  which  the  gear 
box  X  is  made  part  of  the  engine  crank  case  X2.  Access  to 
the  gears  for  adjustment  and  oiling  is  had  through  the  door 
Z.  The  gears  in  this  section  are  shown  in  the  "neutral"  posi- 
tion, that  is,  out  of  mesh,  so  that  the  engine  shaft  can  turn 
without  driving  the  propeller  shaft. 

A  stub  shaft  A  is  connected  with  the  clutch,  the  latter  serv- 
ing to  connect  and  disconnect  the  driving  member  of  the  gear 
box  from  the  motor  when  the  gears  are  being  changed.  This 


72  MOTORS  AND  MECHANISM 

shaft,  which  is  carried  by  the  ball  bearing  U,  extends  only 
by  the  distance  L,  and  is  entirely  disconnected  from  the  main 
shaft  K  except  when  the  car  is  driven  on  the  third,  or  direct 
driven  speed.  At  the  right  end,  the  shaft  is  enlarged  and  the 
gear  teeth  FF  and  G  are  cut  on  the  outer  circumference.  The 
hollow  interior  carries  the  roller  bearings  D  which  in  turn 
support  the  end  E  of  the  main  shaft  K,  so  that  the  left  end  of 
K  is  free  to  turn  within  the  clutch  shaft  A.  This  is  known  as 
the  "Spigot"  bearing,  or  "Spigot"  shaft.  Since  the  two 
shafts  A  and  K  turn  at  different  velocities  at  every  speed 
except  third,  it  is  necessary  that  this  bearing  be  durable  and 
accurate  tg  prevent  noise  and  vibration  that  would  be  caused 
by  slack  or  lost  motion  in  the  bearing.  The  other  end  of  the 
shaft  K  is  carried  by  the  ball  bearing  U2. 

Both  gears,  I  and  I1,  are  prevented  from  rotating  oh  the 
shaft  by  the  long  key-ways  shown,  or  by  squaring  the  shaft 
so  that  I  and  I1  £an  be  moved  back  and  forth  in  the  direction 
of  the  shaft  length.  The  gears  are  rnoved  by  the  gear  shift 
lever  acting  through  the  collars  J  and  J1,  each  gear  being 
moved  independently  so  that  I  can  be  brought  in  mesh  with 
the  teeth  N  or  with  the  teeth  G.  Gear  I1  can  be  meshed  either 
with  the  gear  O  or  the  reverse  pinion  Q.  In  other  words,  the 
gear  I  gives  second  and  third  speeds  while  I1  gives  first  and 
reverse. 

At  the  top  of  each  gear  will  be  seen  two  .arrows  pointing 
to  the  right  and  left,  the  figures  3,  2,  1,  and  R  indicating  the 
direction  in  which  third,  second,  first  and  reverse  occur  when 
the  gears  are  moved  in  the  direction  indicated  by  -the  arrows. 
Moving  I1  to  the  left  gives  first  speed  while  moving  it  to 
the  right  will  give  reverse.  The  operating  lever  system 
prevents  two  speeds  from  being  engaged  at  any  one  time. 

The  countershaft  S  is  at  all  times  driven  from  the  spiggot 
shaft  A  through  the  gear  M  and  the  teeth  F,  this  being  known 
as  the  "constant  mesh"  gear.  The  gears  M,  N  and  O  are 
keyed  rigidly  on  the  shaft  so  that  they  turn  as  one  unit.  The 
sleeve  tubes  T  are  used  to  space  the  gears  on  the  shaft. 
The  countershaft  is  carried  by  the  bearings  U  and  U1,  whicb 


MOTORS  AND  MECHANISM 


73 


THREE  SPEED  SLIDING  GEAR  TRANSMISSION. 

The  Four  Lower  Figures  Show  the  Positions  of  Gears  for  Three  Foreward  Speeds 

and  the  Reverse. 


74  MOTORS  AND  MECHANISM 

in  turn  are  supported  and  protected  from  dirt  by  the  cages 
C1  and  C3. 

At  the  right  will  be  seen  the  reverse  pinion  P  which  is  in 
constant  mesh  with  a  second  reverse  pinion  Q.  If  it  were  not 
for  the  second  pinion,  and  if  the  gear  I1,  came  into  direct 
mesh  with  P,  rotation  would  be  the  same  as  when  in  mesh 
with  gear  O,  since  both  turn  in  the  same  direction.  As  Q 
meshes  with  P,  it  turns  in  the  reverse  direction,  so  that  I1 
will  be  turned  in  the  opposite  direction  when  in  mesh  with  Q 
the  idler. 

The  shift  gear  I  has  the  teeth  I  cut  on  the  outside  and  the 
clutch  teeth  H  cut  on  the  interior.  When  the  gear  I  is  moved 
to  the  extreme  left,  the  interior  teeth  H  engage  with  the 
external  teeth  G  cut  on  the  end  of  shaft  A  so  that  the  clutch 
shaft  A  and  the  main  shaft  K  revolve  as  one  unit  and  at  the 
same  speed,  the  motion  being  transmitted  through  K  and  to 
the  flange  W.  The  universal  joints  are  fastened  to  W  so  that 
the  motion  from  the  transmission  is  given  to  propeller  shaft 
and  hence  to  the  rear  axles.  Any  speed  whether  direct,  for- 
ward geared,  or  reverse  passes  through  K  and  W  into  the 
propeller  shaft  and  rear  axle.  B  and  B1  are  dust  protection 
stuffing  boxes. 

Consulting  the  four  lower  views  we  will  see  the  gear  posi- 
tions giving  first,  second,  third  and  reverse,  the  letters  desig- 
nating the  gears  and  shafts  being  the  same  as  in  the  longi- 
tudinal section.  Starting  with  "First  Speed"  it  will  be  seen 
that  gears  I1  and  O  are  in  mesh  with  gear  I  out  of  mesh  or 
in  "neutral."  Motion  from  A  is  transmitted  through  the  con- 
stant mesh  gears  F  and  M  to  the  countershaft  S,  there  being 
no  direct  connection  between  G  and  I  at  this  time.  With  M 
revolving  the  shaft  S,  the  gear  O  meshing  with  I1  turns  the 
shaft  K  at  a  lower  speed.  The  right  end  of  K  being  connected 
to  the  propeller  shaft.  The  low  speed  is  due  to  the  small 
diameter  of  O  compared  with  I1. 

Throwing  into  second  gear,  the  gear  I1  is*taken  out  of  mesh 
with  O,  and  the  gear  I  is  meshed  with  N,  the  action  being 


MOTORS  ANL^  MECHANISM  75 

similar  to  speed  one,  except  that  increased  speed  is  obtained 
by  making  the  diameter  of.  N  greater  than  O.  In  the  third, 
or  direct  driven  speed,  I1  is  sj:ill  out  of  mesh,  and  the  gear  I 
is  moved  to  the  extreme  left  so  that  the  interior  of  I  engages 
with  the  clutch  teeth  on  G.  This  connects  the  shaft  A  directly 
with  K  so  that  K  and  the  propeller  shaft  revolve  at  full  engine 
speed.  This  is  the  normal  driving  condition. 

In  the  fourth  figure  is  shown  the  reverse,  the  gear  I  being 
withdrawn  and  in  neutral  with  the  gear  I1  in  mesh  with  the 
second  reverse  pinion  Q.  The  direction  of, motion  by  gears 
is  now  F-M-P-Q-I1,  in  order.  It  will  be  noted  that  the  gear 
reduction  is  greater  than  in  any  of  the  other  speeds  since  P 
is  by  far  the  smallest  gear.  In  following  the  cuts,  reference 
should  also  be  made  to  the  longitudinal  section  at  the  top  of 
the  page. 

It  should  be  noted  at  this  point  that  the  car  must  be  fully 
stopped  before  engaging  the  reverse  gear,  as,  owing  to  the 
opposite  directions  of  rotation  of  the  propeller  shaft  and  re- 
verse gears,  when  coasting  there  will  be  danger  of  stripping 
the  teeth.  Severe  stresses  will  also  be  developed  in  the  motor 
and  other  driving  mechanism. 

The  Electric  Gear  Shift. 

Changing  gears  with  the  hand  lever  has  always  been  an 
awkward  proposition,  especially  for  women  who  drive  their 
own  cars.  Shifting  the  gears  has  necessitated  the  removal  of 
one  hand  from  the  steering  wheel,  usually  at  the  time  when 
the' car  must  be  maneuvered  most  carefully  as  in  the  crowded 
city  streets.  The  inconvenient  position  of  the  handle  together 
with  its  long  travel  has  made  gear  shifting  highly  incon- 
venient for  short-armed  people.  In  the  dark,  with  the  gate 
at  a  distance  from  the  operator,  there  is  always  a  chance  of 
getting  into  reverse  while  the  car  is  rolling  forward. 

With  the  electric  gear  shift,  the  gear  changes  are  controlled 
by  push-buttons  placed  directly  on  the  steering  wheel,  so  that 
all  positions  are  directly  under  the  eye  of  the  operator. 


76  MOTORS  AND  MECHANISM 

Changes  can  be  made  without  removing  the  hand  a  great 
distance  from  the  wheel.  It  is  impossible  to  make  mistakes 
owing  to  the  interlocking  connections  between  the  clutch  and 
the  different  speeds.  The  reach  is  so  small  and  the  operation 
so  simple  that  it  can  be  performed  by  a  small  child. 

In  Fig.  A,  an  iron  bar  NS  is  wound  with  a  coil  of  copper 
wire  C,  the  ends  of  the  battery  B  being  connected  with  the 
coil  so  that  the  current  flows  around  the  bar  in  a"  spiral 
path.  The  flow  of  the  current  magnetizes  the  bar  causing  a 
north  pole  at  N  and  a  south  pole  at  S.  This  bar  will  attract 
an  iron  mass  and  will  be  drawn  towards  it.  When  the  cur- 
rent is  broken,  the  magnetism  will  disappear.  In  Diagram  B, 
the  iron  core  A  is  surrounded  with  the  copper  winding  C, 
current  from  the  battery  B  passing  through  the  coil  as  before. 
The  bar  is  again  magnetized. 

An  iron  yoke  E  is  drilled  at  D  so  that  the  bar  A  fits  closely 
but  freely  in  the  hole.  The  magnetic  field  now  passes  through 
the  yoke  and  iron  core  A  in  the  direction  indicated  by  the 
arrows  F,  and  across  the  gap  L  from  N  to  S  between  the 
yoke  and  the  end  of  the  core.  Since  the  unlike  poles  N  and  S 
have  an  attraction  for  each  other,  and  as  the  core  fits  freely 
in  the  hole  D,  the  core  A  will  move  in  the  direction  of  the 
arrow  G  until  N  and  S  come  into  contact.  This  movement 
can  be  repeated  only  by  breaking  the  circuit  and  pulling  the 
core  back  into  its  original  position  with  the  gap  L  between 
the  poles  N  and  S.  This  is,  of  course,  a  single-acting  device. 
A  magnet  in  which  the  core  moves  inside  of  the  winding  is 
known  as  a  "Solenoid." 

Diagram  C  shows  a  solenoid  of  slightly  different  construc- 
tion, the  yoke  E  of  Fig.  B  being  subatituted  by  the  iron  tube 
F,  this  also  acting  to  return  the  magnetic  field  to  the  air 
gap  G.  The  core  A  is  tapered  at  H  to  increase  its  pull  through 
a  long  travel,  the  final  position  of  H  being  at  G.  The  latter 
pole  corresponds  to  N  in  the  diagram  B.  The  distance  of 
travel  is  "d."  The  copper  wire  coil  C  is  wound  on  an  insulat- 
ing spool  R-Q,  there  being  a  small  clearance  between  the  tube 


MOTORS  AND  MECHANISM 


77 


R  and  the  core  A.    The  current  from  the  battery  B  enters  the 
coil  through  the  insulation  posts  I. 

A  gear  L  is  keyed  on  the  shaft  J  so  that  it  is  free  to  move 
back  and  forth  along  the  shaft  but  cannot  turn  on  the  shaft. 
An  arm  O  is  fastened  on  the  core  A  at  P  and  connects  with 
an  annular  groove  at  the  left  of  the  gear.  When  the  core 
moves  to  the  right  in  the  direction  of  arrow  T,  the  arm  O  will 
move  the  gear  L  to  the  position  K  indicated  by  the  dotted  lines. 
The  distances  d  and  L-K  both  represent  the  travel  of  the  core 
and  gear.  With  the  gear  at  L,  and  solenoid  dead,  the  gear  L 


ELEMENTARY   MAGNETIC   GEAR  SHIFT   MECHANISMS. 

will  be  brought  into  mesh  with  the  gear  M  when  current  from 
the  battery  B  is  allowed  to  flow  through  the  solenoid.  To 
take  the  gear  out  of  mesh,  with  this  type  of  solenoid,  the 
circuit  must  be  broken  and  the  core  returned  either  by  hand 
or  by  a  spring.  This  method  of  return  or  dis-meshing  would 
of  course  be  impractical  so  that  it  is  usual  to  employ  a  second 
solenoid  at  the  end  P  of  the  core. 

The  next  cut  shows  the  method  used  for  meshing  the  change 
gears  on  motor  cars,  there  being  two  solenoids  such  as  C  and 
C2  used  at  the  opposite  ends  of  both  iron  cores.  The  trans- 
mission shown,  which  is  of  the  four  speed  type,  has  four 


MOTORS  AND  MECHANISM 


MOTORS  AND  MECHANISM  79 

solenoids  and  two  cores  arranged  so  that  the  two  gears  L  and 
L1  can  both  be  pulled  in  two  directions.  This  transmission, 
as  far  as  the  gears  are  concerned,  is  very  similar  to  the  hand- 
operated  gear  already  described.  As  shown  by  the  side  ele- 
vation, the  solenoid  pairs  are  arranged  so  that  the  pair  C-C2 
is  directly  in  front  of  a  second  pair  C3-C4.  The  core  of  the 
solenoids  C-C2  is  indicated  by  Z-Z2,  while  the  core  of  C3-C4 
is  shown  by  Z3-Z4,  the  rear  core  being  raised  slightly  so  that 
it  can  be  seen.  Section  8-8  shows  an  end  view  in  which  the 
cores  Z2  and  Z3  can  be  readily  seen.  Each  end  of  each  core 
is  given  a  separate  number  so  that  the  ends  can  be  identified. 
Current  for  the  operation  of  the  cells  is  furnished  by  the  stor- 
age battery  B. 

When  the  first  speed  button  I-E  is  depressed,  current  flows 
from  the  battery  terminal  V,  through  wire  U,  through  I-E  and 
terminal  T3  into  the  solenoid  C2.  The  current  returns  from 
the  coil  terminal  T2  to  the  terminal  Y1  of  the  master  switch  on 
its  way  to  the  battery.  The  switch  jaws  S-S1  are  normally 
open,  but  are  brought  into  contact-by  the  clutch  pedal  or  when 
the  clutch  is  released.  When  the  clutch  is  released  the  cur- 
rent flows  momentarily  through  the  coil  C2,  which  draws  the 
core  end  Z2,  sharply  to  the  right,  and  meshes  the  gear  L  with 
the  counter  shaft  gear  P.  The  gear  is  now  in  first  speed. 
Another  mechanism  ;(not  shown)  now  breaks  the  circuit. 

It  will  be  seen  that  the  gear  is  not  thrown  on  depressing 
the  push  button  but  only  when  the  clutch  is  released,  and 
when  the  switch  points  S-S1  are  contacted.  Thus  a  certain 
gear  shift  can  be  determined  on  long  in  advance  of  its  actual 
occurrence,  so  that  when  the  shift  is  needed,  it  will  not  be 
necessary  to  press  the  button  but  only  to  depress  the  clutch 
pedal.  In  this  way  a  car  can  be  manipulated  in  a  crowd  with- 
out using  the  hands  for  anything  else  but  steering.  It  is 
impossible  to  throw  two  gears  at  once  owing  to  the  interlock 
between  the  buttons. 

The  movement  of  the  core  Z-Z2  is  transmitted  to  the  gear 
L  through  the  arm  H  and  the  annular  groove  J.  The  arm 


8o  MOTORS  AND  MECHANISM 

is  attached  to  the  core  at  R.  Movement  of  L  in  the  direction 
of  arrow  "a"  gives  the  low  speed  just  attained,  while  move- 
ment in  the  direction  "b"  gives  the  reverse, — that  is,  when  L 
is  meshed  with  gears  O-O1.  The  reverse  is  made  by  pressing 
button  R-E  which  energizes  solenoid  C,  and  throws  plunger 
Z  in  the  direction  of  arrow  "b."  The  travel  of  the  current 
from  the  battery,  through  button  R-E,  to  the  solenoid,  and 
return  to  battery  is  the  same  as  in  the  first  speed. 

By  means  of  the  two  rear  solenoids  C3-C4,  the  core  Z3-Z4 
acts  on  the  gear  L1  through  the  arm  H1,  shown  by  dot 
and  dash .  lines.  The  arm  is  connected  with  L1  by  a  col- 
lar J1  in  a  groove  at  the  left  of  the  gear.  Movement  in 
direction  of  arrow  C1  meshes  the  clutch  teeth  of  L1  into  the 
teeth  N  of  the  engine  shaft  Q,  giving  direct  or  "high."  Move- 
ment in  direction  "d"  gives  second  speed  by  meshing  L1  with 
the  gear  P1,  the  latter  being  mounted  on  the  counter  shaft  K1. 
The  propeller  shaft  is  attached  to  the  main  shaft  K.  Energiz- 
ing solenoid  C3  moves  L1  into  direct  drive  through  clutch 
teeth  N.  Energizing  C4  gives  second  speed  by  moving  L1  in 
the  direction  of  arrow  d.  Button  2-E  gives  second  speed  and 
button  3-E  gives  high,  these  being  connected  to  solenoids  C4 
and  C3  respectively. 

The  gears  are  neutralized  mechanically  by  a  rather  complex 
system  of  cams  and  shafts,  not  shown  in  our  diagram. 
Two  shafts  connected  with  one  another  by  toothed  cams  and 
operated  from  the  clutch  through  a  lever  mounted  on  the  end 
of  one  of  the  shafts  operates  the  master  switch  in  such  a  way 
that  the  circuit  is  broken  through  the  solenoids  as  soon  as  the 
shift  has  been  made.  This  is  to  economize  the  battery  current. 
When  the  clutch  pedal  is  depressed,  the  circuit  is  completed 
through  the  master  switch,  and  when  the  solenoid  has  made 
the  full  stroke,  it  turns  the  shafts  and  trips  the  spring  con- 
trolled switch  through  a  trigger  arrangement.  The  inactive 
gears  are  brought  into  neutral  by  the  rotation  of  the  shafts 
acting  through  a  lever  engaging  with  a  trip. 


MOTORS  AND  MECHANISM 
Ford  Planetary  Gear. 


81 


In  this  type  of  planetary,  the  engine  drives  through  a  pro- 
peller shaft  to  the  rear  axle  bevel  gear,  all  gears  being  locked 
in  a  mass  and  inoperative  when  on  high  gear,  there  only  being 
one  forward  and  one  reverse  geared  speed.  First  speed  and 
reverse  are  obtained  by  tightening  band  brakes  on  the  gear 
drums.  The  fly-wheel  web  A  carries  the  spindles  of  the  triple 


FORD   PLANETARY   GEAR  TRANSMISSION   WITH   TWO   FOREWARD 
SPEEDS  AND  REVERSE. 


gears  H-G-K,  all  being  spur  gears  and  bound  in  a  unit  mass 
by  rivets  as  shown.  The  mass  revolves  freely  on  the  spindles. 
The  main  drive  pinion  B  is  keyed  to  the  hub  of  the  clutch  drum 
C  which  in  turn  is  keyed  to  the  propeller  shaft  at  the  right. 
The  multi-disc  clutch  C  is  constructed  so  that  throwing  the 
shift  collar  D  will  fasten  the  stub  end  of  the  engine  shaft  (set 
screwed)  to  the  propeller  shaft  through  the  right  hand  flange 


82  MOTORS  AND  MECHANISM 

of  C,  giving  direct  drive  to  shaft.  A  band  brake  over  the  outer 
face  of  C  acts  as  a  transmission  brake. 

To  obtain  the  first  speed,  or  low  gear,  the  drum  E  is  held 
stationary  by  a  band  brake,  thus  holding  pinion  F  stationary, 
cut  on  the  end  of  the  hub  of  drum  E.  As  gear  G  meshes  with 
F  it  rolls  around  it,  ^causing  the  triple  gear  H-G-K  to  revolve 
on  its  spindle.  Gear  H,  meshing  with  pinion  B,  causes  B  to 
revolve  and  with  it  the  propeller  shaft  to  which  it  is  keyed. 
As  F  is  smaller  than  G,  and  H  is  nearly  equal  to  B,  the  propel- 
ler shaft  revolves  at  a  lower  speed  than  the  engine  fly-wheel 
A,  and  in  the  same  direction.  The  small  areas  cross-hatched 
by  dot  and  dash  lines  are  the  bearing  bushings  between  the 
drums. 

By  holding  drum  I  stationary  by  band  brake,  the  pinion  J 
cut  in  its  hub  is  also  held  stationary  with  the  gear  K  rolling 
on  it.  As  K  is  attached  to  H,  and  H  meshes  with  B,  the 
motion  of  the  train  is  again  communicated  with  the  propeller 
shaft,  but  in  a  direction  opposite  to  that  of  the  fly-wheel  A. 

At  first  it  will  be  difficult  to  see  why  holding  the  pinions  F 
and  J  alternately  will  give  opposite  directions  of  rotation  to 
B  since  it  is  evident  that  the  gears  G  and  K  revolve  about  the 
engine  shaft  and  their  own  spindle  in  the  same  direction  in 
both  cases.  Reversal  is  not  due  to  the  reversal  of  the  actual 
direction  of  B  and  H-G-K  but  is  due  to  a  change  in  the  relative 
velocities  between  the  periphery  of  H  and  the  velocity  of  the 
spindles  about  the  engine  shaft. 

It  will  be  noted  that  J  is  larger  than  F,  and  that  K  is  smaller 
than  G,  thus  giving  a  higher  rotational  velocity  to  the  triple 
gears  H-G-K  than  would  be  the  case  with  F  held  stationary. 
The  ratios  of  the  main  gears  H  and  B  are,  of  course,  the  same 
"in  both  cases  with  the  spindles  still  traveling  at  engine  speed. 

With  the  higher  rotational  velocity  of  H-G-K  obtained  by 
holding  J,  the  peripheral  velocity  of  H  at  the  point  where  it 
meshes  with  B  is  now  greater  than  the  velocity  of  the  spindles 
so  that  the  bottom  of  gear  H  forces  B  back  faster  than  the  fly- 
wheel carries  the  mass  forward. 


MOTORS  AND  MECHANISM  83 

Consider  the  top  of  fly-wheel  A  to  be  moving  toward  the 
observer  carrying  with  it  the  spindles  and  the  triples  H-G-K. 
If  H-G-K  were  fastened  on  the  spindles  so  they  could  not 
turn,  they  would  carry  B  with  them  at  engine  speed.  Now 
consider  H-G-K  to  be  given  a  velocity  about  the  spindle  in  the 
same  directional  rotation  as  the  fly-wheel  (top  of  G  moving 
toward  observer)  so  that  the  bottom  of  H  would  move  back 
and  away.  This  would  carry  B  with  it,. and  as  the  velocity  is 
greater  than  that  of  the  fly-wheel,  the  gear  B  and  the  propeller 
shaft  would  be  carried  in  the  opposite  direction  to  the  fly- 
wheel. This  is  exactly  what  happened  when  J  drives  the  triple 
H-G-K  at  a  velocity  greater  than  fly-wheel  speed, 

Gear  Shifting. 

The  operation  of  the  clutch  and  gear-shift  may  generally 
best  be  taken  up  as  one  subject,  for  in  cars  employing  sliding- 
gear  transmissions — and  they  are  the  only  onesvwhich  will  be 
considered  in  the  rest  of  this  article — the  proper  operation  of 
one  depends  largely  on  the  proper  operation  of  the  other. 
The  cluteh,  as  the  reader  probably  knows,  is  for  the  purpose 
of  permitting  the  motor  to  be  readily  and  gradually  connected 
or  disconnected  from  the  transmission;  it  should  never,  except 
in  extreme  cases,  be  used  for  any  length  of  time  as  a  means 
of  increasing  the  power  by  allowing  slipping,  as  little  or  no 
"advantage"  will  be  gained  by  it,  and  the  clutch  js  apt  to  be 
badly  damaged.  When  letting  in  the  clutch  on  starting  care 
must  be  taken  not  to  let  it  grip  suddenly.  Many  clutches 
will  take  hold  smoothly  except  at  the  last  instant,  and  these 
require  special  care.  When  shifting  gears  the  clutch  can 
usually  be  allowed  to  engage  quickly  without  jar  if  the  motor 
has  been  properly  throttled,  and  this  brings  up  the  question 
of  motor  control  when  operating  the  clutch. 

Starting  Off. 

The  very  common  practice  of  speeding  up  the  motor  when 
starting  is  not  to  be  recommended,  except  in  starting  on  a  hill 


84  MOTORS  AND  MECHANISM 

or  when  quick  starting  is  very  important.  A  far  better  way 
is  to  accelerate  the  motor  to  just  a  trifle  faster  than  when 
running  idle,  and  then  to  gradually  open  the  throttle  to  pre- 
vent slowing  the  motor  as  the  clutch  takes  hold.  After  the 
clutch  has  finally  taken  hold  the  motor  may  be  speeded  up 
as  much  as  is  desired.  When  shifting  gears,  disengage  the 
clutch  quickly  and  shift  the  gears  with  a  quick  push  or  pull 
— do  not  "feel"  the  gears  too  much — and  in  the  meantime 
close  the  throttle  almost  tight  and  allow  the  clutch  to  come 
back  quickly  as  soon  as  the  gears  have  been  shifted.  To  many 
this  may  seem  a  poor  method,  but  the  writer  has  found  it 
excellentr  The  throttle  should  be  closed  just  enough  so  that 
when  going  from  a  lower  to  a  higher  speed — from  low  to  sec- 
ond, for  example — the  motor  will  have  slowed  down  almost  to 
the  speed  of  the  clutch  by  the  time  the  gears  have  been 
shifted,  and  so  that  when  going  from  a  higher  to  a  lower  speed 
the  motor  will  only  have  accelerated  to  slightly  more  than  the 
clutch  speed.  In  either  case  as  soon  as  the  clutch  has  taken 
hold  the  throttle  may  be  opened  as  much  as  is  desired.  On 
some  cars  it  will  be  found  difficult  or  impossible  to  use  exactly 
this  method,  and  on  such  cars  it  is  usually  best  to  set  the 
throttle  only  slightly  opened  just  before  making  the  changes. 
In  general  it  is  best  to  make  gear  changes  while  the  motor  is 
running  moderately  slow,  but  no  cars  with  small  motors  or 
any  car  when  in  mud  or  sand,  or  anything  requiring  much 
power,  it  is  better  to  keep  the  motor  speed  quite  high.  Cer- 
tain kinds  of  motors  can  be  run  best  at  much  lower  speeds 
than  others;  a  six-cylinder  motor  can  usually  be  best  run  at 
a  lower  speed  than  a  four-cylinder  motor. 


MOTORS  AND  MECHANISM  85 


CHAPTER  VII 
CARBURETERS  AND  FUEL  SUPPLY 

Carbureter — An  apparatus  used  to  transform  the  liquid  fuel, 
generally  gasolene,  into  a  gas,  and  at  the  same  time  mix  it 
with  such  a  proportion  of  air  as  will  make  it  combustible, 
so  that  it  can  be  used  in  a  gasolene  engine  in  the  same  way 
as  ordinary  coal  gas  and  air  are  used  in  a  gas  engine. 

We  may  use  two  different  methods  to  obtain  a  gas  from 
the  liquid  fuel.  We  may  draw  air  through  or  over  the  sur- 
face of  the  gasolene  and  thus  vaporize  it,  or  we  may  spray 
the  gasolene  into  the  air.  In  either  case  we  have  made  the 
gasolene  combine  with  the  air  so  as  to  form  an  explosive  gas. 

The  Surface  Carbureter. 

When  we  draw  air  through  or  over  the  surface  of  the 
gasolene  we  have  what  are  known  as  surface  carbureters, 
and  these  can  be  divided  into  three  classes : — 

1.  The  type  of  carbureter  in  which  air  is  drawn  over  the 
surface  of  a  body  of  liquid  fuel  and,  evaporating,  carries  off 
with  it  a  certain  proportion  of  that  liquid. 

2.  The  type  in  which   the   capillary   action  of  a  wick  is 
utilized,  and  the  air  is  drawn  through  that  portion  of  the  wick 
above  the  level  of  the  liquid  and  carries  off  with  it  the  evap- 
orated gas. 

3.  The  type  in  which  air  is  drawn  through  the  liquid. 

All  these  types  are  practically  obsolete  as  far  as  automobile 
work  is  concerned.  The  surface  type  of  carbureter  is  un- 
doubtedly one  of  the  most  economical,  but  it  fails  through 
being  incapable  of  rapid  alteration  of  mixture,  and  on  that 
account  has  been  practically  discarded  for  motor  car  work. 

The   Lanchester    (English)    surface   carbureter   consists  of 


86  MOTORS  AND  MECHANISM 

a  large  circular  buadle  of  wicks  threaded  out  at  their  lower 
ends,  these  ends  being  immersed  in  gasolene  in  a  large  inclos- 
ing tank.  Warm  air  is  drawn  through  the  upper  portion  of 
the  bundle  of  wicks,  and  coming  in  contact  with  the  gasolene 
drawn  up  by  capillary  attraction,  becomes  charged  with  gaso- 
lene vapor,  the  actual  proportioning  of  the  mixture  being 
determined  by  means  of  an  air  cock  admitting  more  or  less 
air  to  the  passage  which  conducts  the  mixture  from  the  wicks 
to  the  engine.  The  Ader  type,  also  still  in  use  in  Europe,  is 
much  smaller,  but  has  materially  the  same  action  as  that  of 
the  Lanchester. 

The  bubbling  or  ebullition  type  of  carbureter  is  another 
arrangement  which  though  at  one  time  largely  used,  has  now 
been  entirely  abandoned  for  automobile  work.  The  only  case 
extant  of  this  type  is  a  carbureter  for  crude  petroleum.  In 
this  device  warm  air  is  bubbled  through  oil  heated  to  ebulli- 
tion by  the  exhaust  from  the  engine,  and  so  becomes  charged 
with  petroleum  vapor. 

The  Float-Feed  Carbureter. 

The  spray  or  "float-feed"  type  of  carbureter  is  now  almost 
universally  used.  The  term  atomizer  more  nearly  describes 
the  action  of  the  spray  carbureter  than  any  other  term.  When 
we  force  gasolene  through  a  small  orifice  so  that  it  comes 
out  in  the  form  of  a  spray  we  practically  break  it  up  into 
tiny  atoms,  which  are  mixed  with  the  air  current  which 
causes  the  spray.  These  atoms  of  liquid  fuel  rapidly  become 
vaporized,  and  the  result  is  a  gas  mixture  which  is  highly 
explosive.  The  different  spray  carbureters  vary  from  each 
other  mainly  in  different  means  adopted  for  proportioning 
the  gas  and  air  mixture  for  different  conditions  and  different 
speeds  of  the  engine. 

With  this  construction  gasolene  is  kept  at  a  constant  level 
in  a  jet  nozzle  by  means  of  a  float-feed  device.  The  suction 
of  the  engine  causes  air  to  flow  past  the  jet,  and  the  vacuum 
set  up  produces  a  flow  of  gasolene  from  the  jet,  this  flow 
being  maintained  during  the  suction  stroke  as  a  very  fine 


MOTORS  AND  MECHANISM  87 

spray.  In  this  finely  divided  or  atomized  condition  the  gaso- 
lene is  readily  evaporated  and  taken  up  with  the  inrushing 
air  through  the  inlet  pipe  to  the  motor.  Generally  there  are 
provisions  made  for  admitting  more  or  less  air  to  the  mix- 
ture after  it  comes  from  the  jet,  or  spray  chamber,  this 
arrangement  being  necessary  in  order  that  correct  propor- 
tions of  gasolene  to  air  may  be  approximately  maintained. 

The  multiple  jet  type  of  carbureter  is  a  development  of 
the  ordinary  jet  or  spray  pattern.  With  it  there  are  a  series 
of  jets  having  various  sizes  of  nozzle.  The  smallest  -is  used 
at  the  lowest  speed  of  the  engine,  while  the  increasing  diam- 
eters are  used  either  separately  or  in  conjunction  with  the 
preceding  jets  as  the  speed  of  the  engine  is  increased ;  it  being 
evident  that  at  a  low  speed,  unless  a  very  fine  orifice  is  pro- 
vided, the  spraying  effect  will  not  be  obtained,  while  with 
increasing  speed  and  suction  it  becomes  necessary  to  increase 
the  area  or  orifice  in  order  to  get  the  requisite  amount  of 
gasolene  through. 

Originally  all  carbureters  were  made  with  a  mixture  supply 
and  a  source  through  which  additional  pure  air  might  be 
drawn,  and  regulation  was  accomplished  by  opening  or  clos- 
ing this  supplementary  air  supply  from  the  driver's  seat,  the 
accomplished  results,  of  course,  being  in  accordance  with 
his  skill. 

In  the  early  days  of  the  2Oth  century,  Krebs,  a  French 
engineer,  invented  what  may  be  termed  the  first  automatic 
carbureter  in  which  the  mixture  was  regulated  automatically 
by  the  speed  of  the  engine ;  flexibility  being  thus  obtained  to 
an  extent  hitherto  undreamed  of.  This  invention  paved  the 
way  for,  and  inspired,  a  vast  number  of  others  of  greater  or 
less  merit,  but  it  also  gave  rise  to  one  theory  that  has  since 
been  proved  erroneous,  namely,  that  in  order  to  obtain  the 
best  results  the  engine  should  be  fed  by  a  carbureter  which 
automatically  keeps  the  proportion  of  air  to  gasolene  always 
the  same.  It  was  on  this  principle  that  the  majority  of  de- 
signers worked,  and  the  result  was  that  for  a  considerable 


88 


MOTORS  AND  MECHANISM 


time  there  was  a  deadlock  in  carbureter  design.  Every  one 
had  in  view  an  erroneous  condition  and,  where  their  efforts 
to  satisfy  this  condition  were  the  most  successful,  the  actual 
results  obtained  were  the  poorest.  Experience  since  derived 
indicates  that  in  order  to  obtain  maximum  flexibility  from 
an  engine  the  mixture  must  be  slightly  richer  in  gas  at  low 
speeds,  while  it  may  have  increased  air  proportion  as  the 
speed  develops.  It  is  on  this  principle  that  most  of  the  carbu- 
reters fitted  to  modern  machines  now  operate,  although  such 
operation  is  very  largely  obtained  automatically  from  the 
engine  speed. 

In  all  spray  carbureters  it  is  necessary  to  provide  means  of 

0 


Fig.  1 — Carbureter  Float  Chamber  and  Jet. 

keeping  the  gasolene  at  a  constant  level.  If  it  were  fed 
direct  from  a  tank  to  the  spray  nozzle  it  would  have  a  con- 
stantly varying  weight  of  liquid  behind  it,  as  the  tank  was 
filled  up  or  emptied.  This  would  result  in  varying  sprays, 
irrespective  of  the  varying  suctional  effect  of  the  engine  at 
different  speeds.  It  is  desirable  that  the  inertia  of  the  fluid 
from  which  the  engine  sucks  the  spray  shall  be  constant,  so 
that  some  constant  level  device  becomes  necessary. 

The  float  feed  meets  this  requirement,  and  is  practically 
the  same  in  all  types  of  carbureters. 

A  diagrammatic  view  of  the  float  mechanism  is  given  in 


MOTORS  AND  MECHANISM  89 

Fig.  i.  A  is  the  float  chamber,  supplied  with  gasolene  through 
the  inlet  H.  C  is  a  needle  valve,  shutting  off  or  opening  the 
gasolene  inlet.  There  is  a  collar  around  the  needle  valve,  the 
weight  of  which  keeps  the  latter  normally  closed.  B  is  a 
float  formed  of  a  hollow  chamber  of  light  brass  or  other 
metal  which  floats  in  the  gasolene.  M  is  the  outlet  from  the 
float  chamber  conducting  the  gasolene  to  the  spray  jet  K  in 
the  spraying  chamber  L.  The  level  of  the  gasolene  normally 
stands  at  the  height  of  the  line  J  J,  that  is  to  say,  just  below 
the  top  of  the  spray  nozzle  K.  When  gasolene  is  sucked 
through  the  nozzle  K  by  the  engine  the  level  of  the  gasolene 
in  the  float  chamber  is  lowered,  and  the  float  descends.  In 
doing  so  it  comes  in  contact  with  the  top  ends  of  the  levers 
E  E  pivoted  at  the  points  F  F,  and  depresses  them.  The 
bottom  ends  of  these  levers  then  come  in  contact  with-  the 
collar  on  the  needle  valve  spindle,  raising  it  and  admitting 
more  gasolene  until  the  level  is  regained.  It  will  be  seen  that 
the  action  takes  place  automatically,  and  the  level  of  the  gaso- 
lene in  the  float  chamber  and  in  the  spray  nozzle  is  retained 
at  a  constant  point.  This  device  is  common  to  practically  all 
spray  carbureters,  and  whether  the  gasolene  is  supplied  by 
gravity  from  a  tank  higher  than  the  carbureter,  or  forced 
under  air  pressure  from  a  tank  at  a  lower  level,  does  not  in 
any  way  alter  the  working  of  the  device. 

The  cross-section  of  the  New  Speed  carbureter  is  shown 
herewith,  in  which  the  engine  connection  is  at  the  top,  air  en- 
trance at  the  left,  and  fuel  at  the  right.  The  suction  of  the  en- 
gine raises  the  piston  and  admits  more  or  less  air  through  the 
air  port  at  the  left  as  indicated  by  the  arrows,  and  at  the  same 
time  acts  on  tapered  fuel  valve  B  (Metering  Pin),  so  that  the 
fuel  and  air  are  taken  in  at  the  correctsproportion.  The  meter- 
ing pin  B  is  uncovered  by  the  raising  of  the  piston  A  in  pro- 
portion to  the  suction  created  by  the  engine  piston.  By  an 
annular  port  extending  around  A,  the  air  enters  the  mixing 
chamber  at  uniform  intervals  around  its  circumference.  To 
adjust  for  low  speed,  the  screw  lever  C  is  turned  to  the  left 
for  more  and  to  the  right  for  less  fuel.  When  the  motor  idles 


90  MOTORS  AND  MECHANISM 

properly  with  retarded  spark,  the  carbureter  is  adjusted  for  all 
speeds.  There  are  no  springs,  dials,  jets  or  other  complica- 
tions found  in  the  conventional  carbureter. 

When  idling  the  piston  A  is  in  the  lowest  position,  which 
closes  all  ports  and  allows  fuel  to  enter  through  small  passage 
at  B,  the  annularly  arranged  ports  through  which  the  fuel 
enters  the  mixing  chamber  as  spray  will  be  seen  in  the  center 


FIG.  2.— NEW  SPEED  CARBURETER. 

and  directly  above  the  piston  A.  The  central  tube  D  rests 
on  the  metering  pin  B  and  being  in  one  part  with  the  piston 
A,  admits  fuel  to  its  bore  when  lifted  off  the  metering  pin. 
From  this  point  the  gasolene  ascends  to  the  spray  openings 
above  the  piston.  The  higher  the  piston  lifts  the  more  fuel  will 
flow,  and  the  more  will  be  the  air  admitted  through  the  upper 
ports. 


MOTORS  AND  MECHANISM  91 

Edward's  Carbureter. 

This  carbureter  has  a  number  of  novel  features,  among 
which  is  the  method  adopted  in  handling  the  atomized  gaso- 
lene after  it  has  left  the  nozzle.  It  has  been  found  that  if  the 
particles  of  gasolene  are  broken  fine  enough  to  be  carried  in 


FIG.  3.— EDWARD'S  CARBURETER. 

suspension  by  the  air,  that  they  will  revert  into  large  drops  on 
strikmg  any  solid  surface.  This  is  prevented  in  the  Edwards' 
carbureter  by  the  gas,  great  speed  in  the  Venturi  tube  V, 
shown  by  Fig.  3,  and  then  by  surrounding  it  with  an  outside 
wall  of  air,  which  holds  the  original  gas  in  the  center  and 
out  of  contact  with  the  walls  of  the  device.  In  this  way  the 
particles  delivered  to  the  cylinders  are  exceedingly  fine  and 
capable  of  complete  gasification  on  the  smallest  application  of 
heat.  An  inside  metering  needle  D,  meters  the  fuel  and  keeps 
the  gas  from  touching  at  any  point.  This  needle  is  controlled 
by  the  air  valve  A  by  a  bridge  bar  at  the  lower  end  of  the  air 
valve  spindle.  The  bridge  sets  over  a  collar  on  the  needle 
at  C,  thus  moving  the  metering  needle  directly  with  any  move- 
ment in  the  air  valve  A. 


92  MOTORS  AND  MECHANISM 

At  the  lower  end  of  the  air  valve  spindle  is  the  piston  or 
dash-pot  B  acting  on  the  gasolene  in  this  chamber.  When  the 
throttle  is  suddenly  opened,  the  suction  opens  the  air  valve 
and  through  the  rod,  and  piston  B,  exerts  pressure  on  the 
gasolene,  which  was  drawn  from  the  float  chamber  through 
the  passage  P  (shown  dotted).  The  compression  of  the  gaso- 
lene through  this  movement  compensates  for  the  lack  of 
gasolene  on  quick  throttle  opening  and  increases  the  accelera- 
tion of  the  car  by  forcing  gasolene  into  the  air  stream  around 
the  needle  valve.  A  horizontal  Venturi  tube  E  from  the  float 
chamber  to  the  compression  chamber  allows  the  gasolene  to 
flow  freely  in  one  direction  from  the  float  chamber,  but  <slowly 
in  the  other  so  that  the  compression  will  not  be  interfered 
with  by  the  fuel  supply  from  float  chamber.  This  avoids  the 
use  of  a  check  valve. 

The  single  jet  enters  the  Venturi  tube  V  at  an  angle,  the 
latter  serving  to  increase  the  speed  of  the  air.  The  baffle  BW 
restrains  the  air  from  the  valve  A  to  pass  the  Venturi  in  a 
vertical  direction  so  that  the  gas  will  not  be  blown  to 
one  end  of  the  manifold.  The  heated  primary  air  passes  around 
the  Venturi  not  only  to  warm  the  gas  but  to  keep  the  Venturi 
hot.  After  this  is  warmed  no  heat  is  further  applied,  since  a 
further  rise  in  temperature  would  lower  the  volumetric  effi- 
ciency. A  drain  hole  H  returns  any  condensation  in  the  mix- 
ing chamber  to  the  Venturi,  thus  preventing  loading  with  a 
quickly  opened  throttle.  A  starting  lever  both  regulates  the 
vacuum  and  seals  the  air  valve  to  give  a  rich  starting  mix- 
ture. The  weather  adjustment  is  made  by  a  spring  which 
varies  the  Vacuum  in  the  carbureter.  A  hole  AB  is  to  relieve 
the  vacuum  on  the  air  valve  stem. 

Air  Valve  Types. 

The  Krebs  type  can  today  be  considered  the  simplest  form 
of  carbureter  which  operates  satisfactorily  and  there  are  sev- 
eral different  models  now  manufactured  based  on  the  prin- 


MOTORS  AND  MECHANISM  93 

ciple  of  the  auxiliary  air  valve  only.  In  these  the  problem  is 
worked  out  in  different  ways.  One  manufacturer  uses  a  spring- 
controlled  valve;  another  hopes  to  get  better  results  by  reg- 
ulating the  movement  of  the  valve  by  two  springs,  instead  of 
one ;  still  another  maker  adds  an  air  dashpot  with  the  hope  of 
getting  finer  regulation  and  a  better  functioning  of  the  auxil- 
iary air  valves ;  another  uses  a  dashpot  filled  with  gasoline ; 
and  there  are  others  who  use  metal  balls  to  serve  as  the 
auxiliary  valve ;  while  others  use  what  are  known  as  weighted 
air  valves.  While  they  all  differ  in  the  details  of  working  out 
the  design  they  are,  nevertheless,  based  on  the  basic  princi- 
ple of  the  auxiliary  air  valve  as  originally  worked  out  by 
Krebs. 

Metering  Pin  Class. 

The  next  type  of  carbureter  may  be  referred  to  as  the  meter- 
ing pin  class.  This  division  incorporates  all  that  is  in  the 
air  valve  or  Krebs  classification  but  goes  further  and  inserts  a 
metering  pin,  which  is  a  pin  with  a  bevel  point  in  the  nozzle 
or  jet  from  which  the  gasoline  issues.  This  pin  is  inserted 
with  the  object  of  regulating  the  flow  of  gasoline,  and  is  used 
in  addition  to  the  auxiliary  air  valve  so  that  this  type  incor- 
porates four  basic  features:  the  float  control,  the  auxiliary 
air  valve,  the  nozzle  in  the  air  passage  and  lastly,  the  measur- 
ing pin  in  the  nozzle. 

The  Schebler  metering  pin  is  not  stationary  but  is  designed 
to  be  either  raised  or  lowered  so  as  to  regulate  the  size  of  the 
opening  through  which  the  gasoline  issues  A  conventional 
form  of  it  is  usd  on  one  Schebler  model.  The  metering  pin 
is  linked  with  the  throttle  so  that  as  the  throttle  is  opened  the 
metering  pin  is  raised  out  of  the  nozzle  so  as  to  increase  the 
flow  of  gasoline  in  a  desired  ratio  with  the  increased  air. 

There  are  other  designs  which  move  the  metering  pin 
other  than  by  the  throttle,  in  fact,  in  the  latest  model  T 
Schebler,  the  metering  pin  is  controlled  by  the  auxiliary  air 


94  MOTORS  AND  MECHANISM 

valve.  When  the  valve  moves  downward,  opening,  it  carries 
with  it  the  metering  pin  which  extends  downward  into  the 
jet  and  is  desired  to  increase  the  jet  volume  as  it  is  lowered, 
whereas  in  the  older  Schebler  type  the  jet  volume  is  increased 
by  raising  the  metering  pin.  In  both  the  auxiliary  air  valve 
is  used.  In  one  it  is  controlled  by  a  spring  and  in  model  T  by 
a  dashpot  and  spring. 

There  are  other  carbureters  in  which  the  metering  pin  is 
regulated  by  what  is  known  as  a  metering  air  valve,  in  short, 
a  measuring  air  valve  to  control  the  measuring  gasoline  pin. 
An  example  is  the  Stewart,  in  which  the  metering  valve  is 
rather  a  complex  affair.  The  metering  pin  stands  vertically 
in  the  center  of  the  valve  and  can  be  located  by  the  collars 
on  the  lower  end  meshing  with  the  small  adjusting  wheel  by 
which  the  pin  can  be  raised  or  lowered  as  desired.  Normally 
the  metering  air  valve  by  its  inverted  cone-shaped  top  fills 
the  entire  air  space,  the  only  open  space  for  air  to  pass  being 
through  two  small  openings.  These  passages  have  air  capac- 
ity for  only  very  low  speed  and  as  soon  as  the  motor  require- 
ments exceed  this  volume  the  suction  of  the  engine  begins  lift- 
ing the  entire  air  valve.  The  higher  this  valve  is  lifted  the 
wider  is  the  space  between  it  and  the  metering  pin  and  the 
greater  the  volume  of  gasoline  permitted  to  pass  the  jet.  Also 
the  greater  the  volume  of  air  passing  between  it  and  its  seat. 
By  the  adjustment  provided  at  the  base  of  the  metering  pin, 
the  pin  is  set  to  supply  a  definite  amount  of  fuel  when  the  air 
valve  rests  on  its  seat.  In  order  to  get  the  best  possible  action 
of  the  air  valve  the  lower  end  of  it  is  in  the  form  of  a  piston 
constituting  a  dashpot  operating  in  a  gasoline  well.  This 
dashpot  gives  a  more  uniform  movement  and  prevents  the 
valve  from  fluttering. 


MOTORS  AND  MECHANISM  95 

Multiple  Jet  Carbureters. 

Multiple  jet  carbureters  are  often  employed,  particularly 
where  a  large  range  of  flexibility  is  aimed  at.  In  most  of 
them  there  are  from  two  to  four  jets  which  are  unveiled  to 
the  incoming  air  in  turn,  and  are  either  used  one  at  a  time 
(the  commencement  of  a  second  jet  causing  a  cessation  of 
the  first),  or  else  in  a  series.  In  one  of  the  simplest  and  most 
novel  the  spraying  nozzle  runs  obliquely  from  the  corner  of 
the  float  chamber  into  the '  spraying  chamber,  and  contains 
inside  it  a  loose  toothed  rod,  with  some  five  or  six  serrations. 
In  order  to  reach  the  spraying  chamber  the  gasolene  has  to 
pass  over  the  serrations  cut  in  the  rod,  and  these  offer  a  cer- 
tain amount  of  opposition  to  its  passage.  When  the  speed 
of  the  engine  increases  and* the  suction  becomes  great,  the 
rush  of  the  gasolene  is  interfered  with  to  a  greater  degree 
than  when  the  speed  of  the  engine  is  slow  and  the  suction  is 
slight.  In  other  words,  when  the  gasolene  dashes  up  against 
and  into  the  angle  of  these  serrations,  the  stream  doubles 
back  on  itself,  so  to  speak.  Approximately  correct  mixture 
is  therefore  maintained  at  all  engine  speeds.  Different  sized 
toothed  rods  are  supplied  with  each  carbureter,  so  that  the 
motorist  can  experiment-  for  himself  until  he  gets  the  best 
results. 

Functions  of  the  Carbureter. 

In  answer  to  the  question  of  the  novice,  "What  does  the 
carbureter  do?"  it  may  be  said  broadly  that  the  carbureter 
brings  together  a  portion  of  liquid  gasolene  with  about  8,400 
times  its  volume  of  air,  divides  the  liquid  up  into  so  fine  a 
spray  that  the  mixture  of  the  air  and  liquid  is  made  very 
intimate  and  complete,  and  provides  means  for  keeping  this 
mixture  correctly  proportioned  under  the  varying  working 
conditions  of  the  engine. 

Essential   Parts. 

The  essential  parts  of  a  typical  float-feed  carbureter  may  be 
stated  as  follows :  * 


96  MOTORS  AND  MECHANISM 

1.  A    small    pipe    which    supplies    gasolene    to    the    float 
chamber. 

2.  A  float  which,  when  raised  by  its  buoyancy,  inserts  a 
needle  into,  and  thereby  closes  the  small  supply  pipe. 

3.  Another   small* tube  which   leads  gasolene   away  from 
the  float  chamber  to  the  spray  nozzle. 

4.  The  spray  nozzle  or  jet  which  squirts  the  gasolene  into 
the  middle  of  the  stream  of  air  which  is  on  its  way  to  the 
engine. 

5.  The  air  duct  along  which  the  air  (which  is  very  often 
hot  air)  is  made  to  pass  when  the  engine  makes  its  suction 
stroke.     The  parts  of  this   air  duct  are   called  by   different 
names,  as  follows :     From  the  place  where  hot  air  enters  a 
gauze  filter  at  the  mouth  of  the.  duct  up  to  the  near  neighbor- 
hood of  the  jet,  it  is  perhaps  most  usually  called  simply  the 
hot-air  pipe  and  is  often  made  of  copper.     All  round  about 
the  jet  itself  the  shape  of  the  duct  generally  changes.     It  is 
called  the  spray  chamber,  and  is  usually  made  of  cast  brass. 
Beyond  this,   from   the   spray  chamber  to   the   engine,   it  is 
called  the  inlet,  induction  or  mixture  pipe,  and  is  sometimes 
made  of  copper,  though  sometimes  it  is  a  casting. 

6.  In  the  length  of  the  mixture  pipe  is  often  inserted  a 
device  called  the  auxiliary  air  valve.     This  is  an  automatic 
device  introduced  to  secure  the  different  qualities  of  mixture 
gas  required  under  the  varying  conditions  of  travel. 

7.  Further  on   in  the   length   of  the  ^mixture   pipe  is   the 
throttle  valve,  which  the  driver  can  open  or  close  at  will  by 
moving  a  small  handle  somewhere  on  the  steering  column. 

Quality  of  Mixture. 

The  automatic  extra  air  valve  was  introduced  to  give  to 
the  engine  at  high  speeds  a  diminished  quantity  of  gasolene 
per  stroke.  This  fact  is  often  stated  differently,  namely,  that 
it  was  introduced  to  give  more  air  at  high  speeds  than  at  low 
speeds,  but  this  is  the  wrong  way  to  put  it.  More  air  is 
available,  but  it  is  not  and  cannot  be  taken  by  the  engine,  for 
reasons  which  will  appear  later.  Agreeing  for  the  moment 


MOTORS  AND  MECHANISM 


97 


that  from  40  per  cent,  to  25  per  cent,  less  air  per  stroke  is 
taken  in  at  high  speeds  with  or  without  an  automatic  valve 
(at,  say,  1,500  revolutions),  than  at  low  speeds  (say,  150  revo- 
lutions per  minute).  This  taking  of  less  air  per  stroke  is  the 
chief  and  first  reason  why  less  gasolene  per  stroke  must  be 


n 


The  Schebler  Carbureter— Model  E— Section. 


A  Compensating  air  valve 

B  Float  chamber  ~ 

C  Mixing  chamber 

D  Spraying  nozzle 

E  Needle  valve 

F  Float 

G  Reversible  unioii 

H  Float  valve 

I   Float  connection 

J  .Float  hinge 

K  Throttle 


L  Float  chamber  cover 

M  Air  valve  adjusting  screw 

N  Cork  gasket 

O  Air  valve  spring, 

P  Throttle  lever 

R  Pipe  connection, 

S  Throttle  stop     * 

T  Fixed  air  opening 

U  .Fjoat  valve  cap 

V  Flushing  pin 


given  if  we  wish  to  maintain  what  may  be  called  the  normal 
proportions  of  mixture.  Notice  here  that  we  cannot  hope  to 
avoid  the  taking  of  less  air  even  by  making  smoother  and 
larger  air  passages  and  valves,  since  the  chief  impediment 
is  not  the  friction  of  the  air  against  the  pipe  walls,  but  the 
inertia  and  elasticity  of  the  air  which  prevent  our  giving  it 


98  MOTORS  AND  MECHANISM 

the  necessary  acceleration  in  the  short  time  of  a  suction  stroke 
when  the  engine  is  going  fast. 

Reason  2. — Besides  this  chief  reason,  there  are  subsidiary 
reasons  why  less  than  the  normal  flow  of  gasolene  per  stroke 
is  %  wanted  at  the  highest  engine  speeds.  Thus  there  is  in- 
creased compression  at  high  speeds,  and  this  affects  the  mat- 
ter of  the  most  desirable  mixture  very  appreciably.  The  vol- 
ume sucked  in  is  about  one-third  less,  but  the  compression 
is  effected  ten  times  faster,  and  this  means  a  hotter  compres- 
sion, and  therefore  a  higher  compression,  than  if  the  same 
amount  of  gas  were  compressed  in  the  same  engine  more 
slowly.  To  prove  this,  consider  the  two  extreme  cases  of 
speed,  namely,  infinitely  slow  and  infinitely  fast.  The  dif- 
ference of  pressure  can  be  calculated,  and  it  is  enormous. 
In  an  engine  of  which  the  ratio  of  compression  was  only  3.63 
to  I,  42  -Ibs.  compression  was  calculated  in  the  one  case,  and 
89  Ibs.  in  the  other,  taking  a  supposed  full  charge  of  air  in 
each  case. 

If  the  engine  of  the  example  had  had  the  usual  "five-to-one" 
compression  ratio,  this  would  mean  bad  pre-ignition  with  a 
normal  mixture,  and  a  poorer  mixture  automatically  given 
would  be  necessary  to  save  the  situation  at  high  speeds,  unless 
we  submit  to  the  inefficient  process  of  diminishing  the  com- 
pression by  strangling  the  volume  of  incoming  gas. 

There  is  also  another  fact  which  operates  in  the  same 
direction  as  the  last,  namely,  the  diminution  of  all  small  leak- 
ages of  gas  past  the  piston  rings  and  valves,  spark  plug,  in- 
spection cock,  plugs  and  joints,  when  the  stroke  is  rapid,  all 
making  for  an  increased  compression,  and  therefore,  from  a 
carbureter  point  of  view,  all  pointing  to  the  desirability  of  a 
poorer  mixture  and  therefore  an  extra  air  valve. 

Reason  3. — The  high  and  hot  compression  is  further  en- 
hanced by  the  incomplete  discharge  and  high  temperature 
of  the  unexpelled  residue  of  the  exhaust  from  the  previous 
stroke,  and  the  consequent  greater  initial  temperature  of  the 
heterogeneous  mixture  which  constitutes  the  explosive  charge. 

Reason  4. — Still  another  reason  for  requiring  at  low  speeds 


MOTORS  AND  MECHANISM  99 

more  gasolene  than  the  average  per  stroke,  and  incidentally 
therefore  for  requiring  an  automatic  valve  or  its  equivalent, 
is  based  on  a  totally  different  consideration.  At  the  limit  of 
slowness  with  a  normal  mixture  we  fail,  even  with  a  retarded 
ignition,  to  keep  the  engine  rotating,  because  of  the  evanes- 
cent character  of  the  explosion  pressure  and  the  failure  to 
ignite,  or  at  least  the  incomplete  inflammation  of  the  charge, 
which  would  be  much  throttled  down  for  slow  turning,  and 
therefore,  poorly  compressed.  But  we  find  by  experiment 
that  a  slightly  more  durable  explosion  pressure  is  secured, 
and  much  more  certain  ignition  is  obtained,  when  the  mixture 
is  rich  in  gasolene.  We  therefore  decide  to  employ  a  rich 
mixture  when  running  slowly  and  to  put  up  with  the  draw- 
backs of  a  rich  mixture,  which  are  that  we  do  not  get  com- 
plete combustion  of  the  gasolene.  We  take  the  risk  of  a  little 
smell  and  waste  of  fuel  for  the  sake  of  having  a  "flexible 
engine." 

There  are  many  other  ways  of  regulating  the  quality  of 
mixture  besides  the  use  of  the  automatic  or  auxiliary  air 
valve.  It  is  largely  a  question  for  the  engineer.  The  engine 
and  the  carbureter  must  be  "tuned  up"  together  to  secure 
the  best  results. 

One  important  practical  condition  amongst  many  has 
already  been  mentioned — it  is  known  popularly  as  the  condi' 
tion  which  shows  up  the  "flexibility"  of  the  engine. 

A  "flexible"  engine  is  one  which  continues  doggedly  to  do 
a  modicum  of  useful  work  when  rotating  quite  slowly.  The 
term  "flexible"  does  not  exactly  fit  the  case,  but  it  has  be- 
come established.  This  property  is  assured  not  only  by 
having  the  rich  mixture  at  low  speeds  but  also  by  increasing 
the  number  of  cylinders,  using  mechanically  operated  inlet 
valves,  increasing  the  size  of  the  compression  volume  in 
relation  to  the  piston  displacement,  etc.  These  engine  mat- 
ters again  bear  upon  carbureter  design,  because  they  affect 
the  rate  at  which  the  gas  is  called  for  and  the  manner  and 
frequency  of  that  call — proof  again  that  engine  and  carbureter 
must  be  fitted  to  one  another  as  carefully  as  a  boot  to  a  gouty 


100  MOTORS  AND  MECHANISM 

foot.  It  is  quite  interesting  to  summarize  the  number  of  evils 
which,  though  sometimes  due  to  other  causes,  may  often  be 
due  to  a  badly  adjusted  carbureter.  Sooted  spark  plugs,  boil- 
ing of  radiator,  eroded- exhaust  valves,  loss  of  power,  mis- 
firing, waste  of  gasolene,  failure  to  pick  up  until  some  mo- 
ments after  any  new  position  of  the  throttle  has  been  adopted, 
smelly  exhaust,  "popping"  behind  the  inlet  valve,  explosion 
in  the  exhaust  box,  pre-ignition  with  resultant  damage  to 
crank-shafts  or  connecting  rods,  failure  of  the  engine  to  stop 
when  the  spark  has  been  interrupted,  etc.,  etc. 

In  view  of  all  this,  it  is  small  wonder  that  manufacturers 
have  been  kept  busy  experimenting  with  innumerable  meth- 
ods and  suggestions  for  varying  the  quality  of  the  mixture 
in  some  manner  remotely  according  to  the  conditions  of  its 
employment. 

A  Cause  of  Heavy  Gasolene  Consumption. 

One  source  of  excessive  gasolene  consumption  is  the  heat- 
ing of  the  carbureter  to  a  much  higher  degree  than  is  neces- 
sary, so  that,  independently  of  the  suction  by  the  motor  a 
comparatively  large  quantity  of  gasolene  is  drawn  through 
the  jet  in  the  form  of  pure  vapor.  This  added  to  the  subse- 
quet  charge  of  gasolene  drawn  through  the  jet  by  the  suc- 
tion -of  the  engine  makes  up  the  large  quantity  of  liquid 
used.  The  resultant  cylinder  charge  is,  of  course,  much 
richer  than  is  necessary  or  good  for  the  engine,  as  sooty 
valves  and  plugs  nearly  always  result.  We  use  the  words 
"nearly  always"  advisedly,  as  some  engines  have  their  valves 
and  plugs  so  placed  that  they  are  automatically  cleaned  by 
the  exhaust  gases,  one  charge  sweeping  before  it  the  soot  de- 
posited by  the  previous  charge.  Again,  in  other  engines,  the 
plugs,  or,  perhaps,  the  valves  alone,  are  so  placed  as  to  pre- 
vent the  accumulation  of  carbon  deposit.  We  mention  this, 
as  probably  some  readers  will  wonder  why  their  valves  and 
not  their  plugs  become  dirty  or  vice  versa. 

Having  given  a  probable  cause  of  the  trouble,  we  suggest 
a  remedy  which,  to  many  readers,  will  be  perfectly  obvious, 


MOTORS  AND  MECHANISM  101 

and  that  is  to  cut  off  the  hot  air  or  water,  as^the  case  may 
be,  from  the  heating  chamber  by  means  of  a  simple  cock. 
It  is  only  when  running  through  a  keen  frosty  air,  or  when 
the  atmosphere  is  heavily  charged  with  moisture,  that  the 
heating  chamber  is  actually  required,  yet  on  many  engines 
no  provision  is  made  for  cuttiftgj  qffi,  tfre;sourcej>  oi  heat,  hence 
the  increased  gasolene  consumption.  * 


Letting-  jn 

There  is  no  doubt  that  many  cars  waste  a  lot  of  gasolene 
simply  because  the  carbureters  do  not  supply  sufficient  air. 
In  this  matter,  car  owners  might  well  take  an  example  from 
motor  cyclists.  Speaking  generally,  motor  cyclists  realize  the 
advisability  of  using  as  weak  a  mixture  as  possible,  and  after 
a  motor  cyclist  has  passed  his  novitiate  it  is  quite  the  usual 
thing  to  find  that  he  has  so  altered  or  adjusted  his  carbureter 
that  he  can  always  command  an  adequate  supply  of  air,  as 
very  few  cycles  are  turned  out  with  provision  for  a  full  sup- 
ply. It  i's  not  merely  a  question  of  economy  of  gasolene, 
though  that  is  quite  an  item,  but  in  many  cases  more  power 
can  be  obtained  from  the  engine,  and  it  keeps  much  cleaner, 
while  the  valves  keep  cooler  and  the  smell  from  the  exhaust 
is  much  less  if  the  weakest  possible  mixture  is  used.  An 
extra  air  inlet  is  therefore  a  good  thing  and  there  are  many 
ways  of  increasing  the  air  supply. 

Water  in  Air  Pipe. 

The  air  supply  pipe  to  carbureters  of  most  cars  is  arranged 
so  that  the  pipe  can  be  open  to  the  air,  or  made  to  take 
its  air  from  round  the  exhaust  when  the  temperature  of  the 
outer  air  is  so  low  that  good  running  cannot  be  obtained 
unless  the  air  be  heated.  On  many  cars  the  air  pipe  is  high 
up  and  well  out  of  the  way,  but  there  are  a  number  which 
have  the  pipes  so  arranged  that  when  the  car  is  washed,  some 
of  the  water  may  splash  into  it  at  the  cold  air  slot.  We 
have  come  across  instances  in  which  this  has,.  occurred,  so 
that  the  water  has  been  sucked  into  the  carbureter;  then  if 
the  engine  does  not  run  well,  it  has  been  assumed  that  there 


102  MOTORS  AND  MECHANISM 

was  water  in  the  gasolene,  though,  as  a  matter  of  fact,  any 
small  quantity  which  might  enter  through  the  induction  pipe 
would  really  do  no  harm.  At  the  same  time,  when  one  sees 
water  dropping  from  the  carbureter,  it  is  only  natural  to 
assume  at  the  first  glance  that  it  is  caused  by  water  in  the 
gasolene.  However,  we  .-give  the  hint  for  what  it  is  worth ; 
as  if  the  idea  is  once' obtained  that  there  is  water  in  the  gaso- 
lene, a  lot  of  •  rouble"  ^viU'be  tsken  for  nothing.  There  is  also 
a  certain  amount  of  condensation  in  the  induction  pipe,  and 
beads  of  moisture  may  be  noticed  in  it  from  this  cause. 

Flooding  Carbureters. 

When  persistent  flooding  of  carbureters  occurs,  it  is  gen- 
erally due  to  one  of  two  things:  Failure  of  the  needle  valve 
to  seat  properly,  which  can,  of  course,  be  overcome  by  grind- 
ing in  the  valve,  or  to  a  punctured  float,  which  allows  a  small 
quantity  of  gasolene  to  enter,  and  thus  upset  the  balance  and 
allow  the  gasolene  level  to  rise  higher  than  it  should  do,  and 
consequently  to  flood.  This  can  be  easily  discovered  by 
shaking  the  float,  when  the  liquid  can  be  heard  inside.  To 
find  the  hole  and  get  the  gasolene  out  is  somewhat  difficult, 
but  the  following  is  the  simplest  way:  The  float  should  be 
put  into  very  hot  water  and  held  beneath  the  surface.  The 
heat  causes  the  gasolene  to  gasify  and  be  driven  out  through 
the  small  hole,  when  the  issuing  bubbles  will  make  it  clear 
where  the  hole  is.  The  float  should  be  thoroughly  cleared 
of  gasolene,  and  the  hole  stopped  up  with  solder.  In  doing 
this,  it  is  a  mistake  to  put  as  little  solder  as  possible  on  to  the 
hole,  but  the  job  should  be  done  thoroughly  and  be  cleaned 
afterwards  with  fine  emery  paper.  Of  course,  care  must  be 
taken  not  to  allow  too  much  solder  to  remain  on,  so  as  to 
upset  the  balance  of  the  float,  and  not  to  allow  the  solder  to 
get  into  the  float.  Silver  solder  is  better  than  soft  solder  for 
this  purpose.  If  after  the  hole  has  been  closed  .a  slight  leak- 
age follows  which  it  is  impossible  to  locate,  a  good  method 
of  preventing  further  trouble  is  to  give  the  whole  float  a  good 
coating  of  nickel  by  electroplating  it.  This,  closes  up  the 
small  porosities  better  than  any  solder  will  do. 


MOTORS  'AND  MECHANISM 


103 


With  carbureters  of  the  Longuemare  type,  with  a  weighted 
needle,  flooding  is  sometimes  due  to  a  third  cause.  The 
weight  occasionally  bears  on  the  seating,  and  does  not  allow 


The  Schebler  Carbureter— Model  F— Section. 


A   Compensating  air  valve 

S    Pivot  screw 

B    Float  chamber 

T    Float  valve  cap 

C    Mixing  chamber 

U    Flushing  pin 

D   Spraying  nozzle 

V    Lock  nut 

E    Needle  valve 

W  Needle  valve  hex  connection 

F    Float 

X   Spring  cam  casting                                       • 

C   Reversible  union 

Y    Eccentric  high  speed  adjustment 

H   Float  valve 

Z    Air  valve  shutter  lever 

I     Needle  valve  adjusting  screw 

1     Air  valve  butter-fly  disk                               . 

J     Float  lever 

2     Spring 

K   Throttle 

3     Lock  screw 

L    Needle  valve  retainer 

4     Cam  spring 

M   Air  valve  adjusting  screw 

5     Lock  nut  for  bowl 

N  Cork  gasket 

6     Air  valve  cap 

O    Air  valve  spring 

7     Needle  valve  retaining  spring 

P    Throttle  lever 

8     Needle  valve  spring 

Q    Needle  valve  lift  lever 

9     Constant  air  opening 

R    Throttle  stop 

the  needle  to  seat  properly.  The  result  is  that  flooding  occurs 
either  continuously  or  intermittently  when  the  motor  is  run- 
ning, as  then  the  vibration  shakes  the  needle  from  its  seat. 

Warming  the  Carbureter. 

A  kink  applied  very  successfully  for  starting  the  engine 
when  the  atmosphere  is  chilly  is  simply  to  fill  an  ordinary 
india-rubber  hot-water  bottle  and  apply  it  as  far  round  the 
carbureter  as  possible,  leaving  it  there  for  a  sufficient  period 


104  MOTORS  AND  MECHANISM 

to  enable  the  carbureter  itself  to  draw  some  heat  and  thus 
assist  vaporization.  Another  method  is  to  wrap  around  the 
carbureter  some  absorbent  material,  such  as  large  size  lamp 
wick,  which  can  be  carried  for  the  purpose,  and  to  pour  over 
this  hot  water,  repeated  applications  of  which  will  raise  the 
temperature  of  the  carbureter  even  higher  than  will  be  ob- 
tained by  the  usual  heating  by  a  branch  from  the  exhaust. 

The  Freezing  of  Carbureters. 

"During  a  snap  of  frost,"  writes  an  enthusiastic  automo- 
bilist,  "we  had  an  experience  with  one  of  our  cars  which 
may  prove  a  warning  to  others.  While  the  cooling  water  cir- 
culating system  was  in  a  sufficiently  warm  place  to  prevent 
its  freezing  up,  yet  it  did  not  protect  the  carbureter  from 
the  effects  of  the  frost.  This  particular  carbureter  has  a  hot 
water  jacket  around  the  mixing  chamber,  which  is  in  close 
proximity  to  the  float  feed  chamber.  A  single  cock  is  pro- 
vided to  prevent  the  water  circulating  round  the  jacket  when 
extra  heat  is  not  required,  but  it  was  impossible  to  drain  the 
water  from  the  jacket.  The  low  position  of  the  carbureter, 
and  the  lower  temperature  occasioned  by  the  near  presence  of 
gasolene,  were  too  much  for  the  water  around  the  carbureter, 
and  it. froze  up.  A  natural  consequence'  was  that  something 
had  to  go,  and,  fortunately,  the  weak  spot  was  found  at  a 
plate  soldered  over  a  clearing  hole  in  the  water  jacket.  This 
gave  way,  and  when  the  thaw  came  we  had  a  fountain  display 
beneath  our  engine  bonnet.  As  a  protection  against  similar 
occurrences,  we  had  an  extra  cock  put  into  the  circulation 
pipes  on  the  other  side  of  the  carbureter,  and  a  drain  cock 
put  into  the  lowest  point." 

When  the  Jet  is  Blocked. 

Few  owners  care  to  take  down  a  carbureter  by  the  roadside, 
especially  as  some  carbureters  appear  to  be  constructed  with 
the  sole  object  of  making  it  as  difficult  as  possible  to  get  at 
the  jet.  When  the  jet  is  blocked  it  is  always  well  to  try 
flooding  before  taking  the  trouble  to  pull  the  carbureter  to 
pieces.  Many  automobilists  know  this  little  wrinkle,  but 


MOTORS  AND  MECHANISM  105 

plenty  do  not.  It  is  simply  a  matter  of  holding  the  float 
down  or  up,  according  to  which  way  the  gasolene  is  admitted, 
so  that  the  full  head  of  gasolene  in  the  tank  may  come  through 
to  the  jet.  In  nine  cases  out  of  ten  it  will  free  it — possibly 
only  temporarily,  but  still  enough  to  enable  one  to  get  along 
and  to  postpone  the  taking  down  of  the  jet  till  one  gets  home. 
When  once  the  engine  has  been  got  going  again  one  can  keep 
a  careful  ear  upon  its  running,  and  directly  it  shows  signs 
of  flagging,  race  it  a  bit,  and  race  it  with  the  extra  air  inlet 
(if  such  is  provided)  closed.  This  puts  so  strong  a  suction 
on  the  jet  that  it  will  often  remove  the  obstruction,  and  that 
without  stopping  the  car. 

Choked  Carbureters. 

One  of  the  most  exasperating  of  minor  troubles  which  can 
fall  to  the  lot  of  the  motorist  is  to  have  a  partially  choked 


The  Schebler  Fuel  Strainer — Cross  Section. 


gasolene  jet  in  the  carbureter.  If  the  jet  were  wholly  blocked 
up  and  the  engine  could  not  be  run  at  all,  one  would  naturally 
go  to  the  carbureter  (if  not  at  once,  directly  after  testing 
the  ignition),  and  the  cause  of  the  trouble  would  be  revealed. 
On  the  other  hand,  when  there  are  particles  of  foreign  matter 
floating  about,  they  will  keep  more  or  less  clear  of  the  jet, 


106  MOTORS  AND  MECHANISM 

but  they  are  never  far  away.  You  flood  the  carbureter  and 
start  up  the  engine,  which  runs  merrily  for  a  few  revolutions, 
coughs,  chokes,  and  stops.  What  has  happened?  Those  free 
bits  of  dust  which  were  merely  agitated  by  the  action  of  flood- 
ing the  carbureter  have  by  the  constant  suck  exerted  by  the 
engine  been  drawn  up  into  the  jet  and  effectually  blocked  it. 
The  engine  being  stopped,  the  bits  fall  away  from  the  jet 
again,  and  so  the  process  of  numberless  startings  up  of  the 
engine  is  performed.  Now,  if  the  ignition  be  found  in  order, 
and  the  gasolene  feed  to  the  carbureter  be  clear,  it  is  nearly 
always  advisable  to  proceed  to  the  jet  and  clear  it  out  straight 
away.  While  the  jet  is  out,  run  some  gasolene  through  the 
jet  orifice  to  wash  away  any  particles  which  may  be  left 
behind.  The  jet  being  clear,  it  may  be  replaced  and  flooded, 
in  order  to  ascertain  that  all  is  perfectly  in  order. 

Attention  to  Automatic  Carbureters. 

Automatic  carbureters,  like  many  other  good  things,  re- 
quire keeping  thoroughly  up  to  the  mark,  otherwise  they  are 
apt  to  become  a  source  of  trouble.  A  great  many  of  the  auto- 
matic carbureters  now  in  use  have  a  sliding  plunger  or  piston, 
the  suction  of  the  engine  on  the  plunger  causing  a  greater  or 
less  opening  of  extra  air  inlets.  Now,  when  taking  in  air 
through  these  extra  orifices,  of  codrse,  whatever  dust  or  other 
foreign  matter  is  present  in  the  air  is  taken  in  past  the  auto- 
matic piston,  and,  since  moisture  usually  condenses  about 
this  part,  the  dust  is  there  deposited.  The  effect  of  this  is 
to  cause  the  piston  to  stick  or  work  erratically,  this  having 
a  bad  effect  on  the  running  of  the  engine,  apart  from  increased 
gasolene  consumption.  Some  automatic  pistons  are  made  so 
that  they  can  be  readily  detached,  so  that  in  such  a  case  all 
that  it  is  necessary  to  do  is  to  see  that  the  piston  is  washed 
out  pretty  frequently,  but  in  cases  where  such  cannot  be 
done  it  is  a  good  plan  to  get  a  small  syringe  and  wash  the 
piston  orifices  thoroughly  with  a  spray  of  gasolene,  which 
does  the  job  quite  as  well.  Of  course,  in  doing  this,  care  must 
be  taken  that  no  naked  lights  are  in  the  vicinity  of  the  car- 


MOTORS  AND  MECHANISM  107 

bureter,  nor  until  the  gasolene  vapor  is  thoroughly  removed 
must  a  lighted  match  be  thrown  on  the  floor,  otherwise  a  fire 
is  certain  to  ensue. 

Another  frequent  cause  of  trouble  with  •  automatic  car- 
bureters is  that  due  to  the  spring  losing  its  tension  or  in 
other  ways  getting  out  of  adjustment.  There  is  usually  a 
small  nut  or  pair  of  nuts  fitted,  which  can  be  screwed  up  or 
down  to  alter  the  tension  or  pressure  on  the  piston  controlling 
spring,  and  sometimes  such  nuts  are  rather  likely  to  shake 
loose  and  alter  their  position  relative  to  the  stem  on  which 
they  are  screwed,  thus  altering  the  spring  tension.  These 
should  be  examined  from  time  to  time  to  assure  the  user 
that  they  are  in  the  correct  position.  When  the  spring  be- 
comes too  weak,  either  a  new  spring  must  be  fitted,  or,  as 
a  temporary  measure,  the  old  spring  can  be  removed  and 
carefully  stretched  and  then  replaced,  the  adjustment  being 
made  by  means  of  the  nuts,  as  before  mentioned. 

Air  Inlet  Gauzes. 

Assuming  the  gauze  to  take  up  three-quarters  of  the  air 
inlet — which  is  usually  the  case — the  area  of  the  gauze  should 
be  made  about  four  times  as  large  as  the  actual  air  inlet. 

This  is  provided  for  by  supplying  a  funnel  over  the  mouth 
of  which  the  gauze  is  to  be  fixed.  As  an  alternative,  if  the 
funnel  cannot  be  fitted,  the  gauze  should  be  made  into  a  cone 
and  slipped  inside  the  pipe,  as  in  this  way  the  area  of  the 
gauze  is  made  sufficiently  large  to  allow  the  right  quantity 
of  air  to  pass  through  it. 

Gauzes  fitted  to  the  air  intake  of  any  kind  of  carbureter 
should  be  frequently  cleaned.  Otherwise  they  rapidly  choke 
up  with  oil  and  dust,  the  result  being  that  insufficient  air 
passes  to  the  carbureter,  which  means  that  the  suction  on  the 
jet  is  increased  and  more  gasolene  taken  to  the  engine  than 
should  be  the  case,  resulting  in  heavy  consumption,  boiling 
water,  dirty  engine,  overheating,  and  loss  of  power. 

It  is  often  remarked  that  unless  a  gauze  is  fitted  the  car- 
bureter will  choke  up,  In  such  a  case  the  fact  is  overlooked 


108  MOTORS  AND  MECHANISM 

that  chokage  in  a  carbureter  is  due  to  chokage  of  the  gaso- 
lene passage,  and  not  to  the  air  passages,  and  that  dust  getting 
into  the  carbureter  by  way  of  the  air  intake  cannot  get  into 
the  jet  or  gasolene  passage.  As  a  rule  the  only  damage  that 
dust  can  do  is  to  get  into  the  engine  and  pass  out  through 
the  exhaust  valve.  While  in  the  engine  it  can  do  little  harm, 
though  a  deposit  may  be  formed  on  the  piston  bead  by  it.  In 
one  case  it  appeared  to  be  carbon,  in  consequence  of  the  bad 
quality  of  the  lubricating  oil.  An  analysis  of  the  deposit, 
however,  proved  that  it  was  caused  almost  wholly  by  dust- 
laden  air  which  was  drawn  in  through  the  air  intake,  which 
was  not  protected  by  gauze. 

Obviously,  the  best  thing  to  do  is  to  fit  a  large  gauze, 
which  is  detachable,  and  to  keep  it  clean. 

Gauze  in  the  Induction  Pipe. 

From  time  to  time  many  experiments  have  been  made  with 
gauze.  Occasionally  a  wire  gauze  disk  is  put  in  the  inducr 
tion  pipe,  and  gauze  has  been  tried  in  the  carbureter.  The 
idea  is  that  the  mixture  shall  be  more  thoroughly  atomized 
by  passing  through  the  fine  meshes  of  the  gauze.  It  may 
be  safely  said  that  the  matter  is  one  of  experiment,  and  in 
some  Longuemare  carbureters  it  has  been  found  a  really 
distinct  advantage.  In  this  carbureter,  the  extra  air  inlet  is 
below  the  jet,  and  the  air  holes  are  covered  by  a  couple  of 
segments,  on  the  top  of  which  is  a  perforated  brass  disk.  This 
disk  is  just  above  the  jet,  and  above  or  below  the  disk  it  is 
very  easy  to  place  three  or  four  disks  of  gauze.  Those  who 
know  the  Longuemare  carbureter  will  understand  at  once 
how  easily  this  can  be  done.  It  has  been  found  that  the 
effect  of  the  gauze  was  twofold.  It  has  reduced  gasolene 
consumption,  and  made  it  possible  to  run  the  engine  at  a 
considerably  lower  speed  when  desirable ;  this  applies  whether 
the  engine  is  running  light  or  driving  the  car.  The  improve- 
ment in  running  appears  to  be  due  to  the  more  perfect  atomi- 
zation  of  the  mixture,  as  the  whole  of  the  gasolene  and  all 
the  additional  air  have  to  pass  through  the  gauzes.  There 


MOTORS  AND  MECHANISM 


109 


is  also  a  sort  of  wick  effect,  as  the  three  or  four  thicknesses 
of  gauze   make  a  pad   immediately  above  the  jet,   which   is 


The  Schebler  Carbureter — Model  H — Section. 


A  Compensating  air  valve 

complete  (4  pcs.) 
B   Low    speed    adjusting 

screw 

C   Low  speed  lockscrew 
D  Float  valve  cap 
E  Float  chamber  lock  nut 
F  Reversible  union 
G  Reversible  union  nipple 
H  Lift  lever  shaft  retainer 
[    Float  chamber 
J    Mixing  chamber 
K  Constant    air    Opening 

connection 
L  Butterfly  valve  starting 

lever 

M  Spring  cam  casting 
N  Eccentric    high    speed 

adjustment 
O  Cam  spring 
P  Throttle  stop 


Q  Adjus'ble  throttle  lever 
casting 

R  Throttle  valve  stem 

S  Throttle  valve  butterfly 
disk 

T  Needle  valve  retainer 

U  Needle  valve  lift  lever 

V  Cam  roller 

W  Needle,  valve  adjusting 
screw 

X  Needle  valve  adjust- 
ment retainer 

Y  Needle  valve 

1  Float 

2  Float  valve 

3  Float  valve  lever 

4  Air     valve      adjusting 

screw 

5  Leather  friction  disk 

6  Friction  spring 


always  saturated  with  gasolene,  and  seems  to  afford  a  small 
reserve,  which  results  in  a  better  pick-up  after  slowing  on  the 


110  MOTORS  AND  MECHANISM 

throttle.  It  is  obvious  that  the  gauze  must  have  a  wire- 
drawing effect,  and  thereby  put  a  certain  amount  of  negative 
work  upon  the  engine,  but  this  negative  effect  is  more  than 
nullified  by  the  superior  atomization,  so  that  the  maximum 
power  and  speed  of  the  engine  is  not  reduced  in  any  way, 
and  the  advantages  of  smoother  running  at  low  speeds  and  a 
quicker  pick-up  are  gained. 

The  Breeze  Carbureter. 

The  Breeze  carbureter  is  a  good  example  of  the  modern 
carbureter,  and  is  therefore  fully  illustrated  herewith.  The 
manufacturers  claim  that  this  carbureter  is  equally  adaptable 
to  all  engines  and  that,  when  adjustments  are  once  properly 


BURSfeft 
NE.CWOW, 


The  Breeze  Carbureter— Check  Valve. 

made,  it  will  deliver  the  right  kind  of  mixture  to  the  engine 
at  all  speeds  at  which  it  will  work  without  change  of  adjust- 
ment. 
The  special  features  are  stated  as  follows: 

1.  Simplicity:  all  adjustments  are  independent  and  when 
made,  stay  set. 

2.  Gasolene  and  air  adjustments  both  placed  on  top  of  the 
carbureter,  the  gasolene  valve  having  figures  and  graduations 
stamped  on  a  dial  head  indicating  its  exact  position. 


MOTORS  AND  MECHANISM 


111 


3.  Non-fluttering  auxiliary  air  valve  maintains  an  even  ad- 
dition of  air  to  the  mixture  at  high  speeds. 

4.  Central  draught  for  main  air  and  gasolene  spray  prevents 
changing  of  fuel   level  on   grades.     The  gasolene   is   always 
there. 

5.  Peculiar   construction   of   the   needle   valve   causes   the 
breaking  up  of  the  fuel  into  the  smallest  particles  possible, 
giving  at  the  same  time  economy  and  power. 


The  Breeze  Carbureter,  Showing  Main  Air  Supply  and 
Strangling  Tubes. 

6.  Choice  of  vertical  or  horizontal,  or  male  or  female  con- 
nection to  engine. 

7.  Carbureter  easily  detachable  from  flange  of  engine  pipe 
connection. 

8.  Spun  brass  float,  obviating  all  need  of  adjusting  fuel  level, 
which  is  a  frequent  trouble  with  a  cork  float. 

9.  Interchangeable  main  air  tubes  giving  a  wide  range  of 


112  MOTORS  AND  MECHANISM 

main  air  supply  and  still  maintaining  the  correct  cone-shaped 
air  passage. 

10.  Simple  and  easily  detached  hot  air  attachment. 

Principle — The  Breeze  carbureter  consists  of  a  fuel  chamber 
provided  with  a  float  feed  device  to  maintain  the  fuel  level 
always  at  a  point  just  below  the  spray  nozzle,  which  is  con- 
nected by  a  cross  tube  to  the  fuel  chamber;  when  air  is  sucked 
through  the  conical-shaped  main  air  tube  by  the  engine,  a  pro- 
portion of  gasolene  is  drawn  up  into  the  engine  with  it.  This 
proportion  is  determined  by  the  adjustment  of  the  needle  valve. 
As  the  suction  increases  when  the  throttle  is  opened  or  the 
engine  runs  faster,  the  proportion  of  gasolene  taken  up  is 
greater  than  it  should  be,  so  the  auxiliary  air  valve  is  pro- 
vided and  arranged  to  open  against  a  spring  and  admit  pure 
air  according  to  the  increased  suction  of  the  engine.  By 
proper  adjustment  of  this  valve  spring,  it  is  claimed,  the  car- 
bureter can  be  made  to  furnish  a  uniform  mixture  to  any 
engine.  A  valve  or  throttle  is  provided  to  govern  the  amount 
of  mixed  gas  delivered  to  the  engine. 

The  fineness  of  the  mixture  of  gasolene  and  air  determines 
the  economy  and  also  the  maximum  power  obtainable  from 
a  given  size  carbureter.  A  certain  minimum  of  suction  is  nec- 
essary on  low  engine  speeds;  and  adjustment  to  make  different 
model  engines  obtain  this  is  provided  by  using  different 
sized  strangling  tubes  for  the  air  intake  around  the  spray 
nozzle. 

"Auxiliary  Air  Valve — An  auxiliary  air  valve  is  provided  to 
furnish  the  engine  with  more  pure  air  on  medium  and  high 
speeds.  On  low  speeds  this  valve  roust  stay  closed  and  the 
Venturi  tube  around  the  spray  nozzle,  which  the  Breeze  people 
have  used  since  1904,  is  §mall  enough  to  keep  the  suction  suffi- 
cient to  give  a  good  mixture  and  is  automatic  within  a  mod- 
erate range  of  low  speeds,  but  on  medium  and  high  speeds  the 
mixture  gets  too  rich  in  fuel.  Fuel  is  necessary  for  power, 
but  must  have  air  in  the  right  proportion  to  burn  with  it. 

The  auxiliary  air  valve  is  held  to  its  seat  by  a  spring,  and 
the  engine  suction  on  medium  .and  high  speeds  opens  it  to  that 


MOTORS  AND  MECHANISM 


113 


distance  which  the  spring  tension  permits.  This  adjustment 
properly  made,  the  suction  of  the  engine  regulates  the  mix- 
ture automatically  by  pulling  the  valve  open  to  the  proper  dis- 
tance. 

To  adjust  the  valve,  loosen  the  air  valve  adjusting  lock 
nut,  turn  the  slotted  stem  to  the  left  to  stiffen  the  spring  and 
decrease  the  air,  to  the  right  to  weaken  it  and  give  more  air. 
Be  careful  in  weakening  the  spring  and  giving  more  air  not 
to  weaken  it  so  much  that  the  valve  does  not  seat.  Air  must 


OCK 
NUT 


CYLINDER 


The  Breeze  Carbureter — Auxiliary  Air  Valve. 

not  get  in  on  low  speeds  or  starting  will  be  almost  impossible. 
Lock  the  adjustment  securely. 

This  device  is  simple  and  needs  no  attention  unless  both  oil 
and  sand  get  on  it  at  the  same  time,  in  which  case  it  will  stick 
and  must  be  cleaned  out.  Leave  all  parts  dry.  Do  not  oil 
it.  If  this  happens  it  would  be  advisable,  for  the  good  of  the 
engine,  to  protect  the  carbureter  by  an  apron.  The  amount 
of  sand  required  to  spoil  the  working  of  the  air  valve  would 
be  very  bad  for  the  engine  if  allowed  to  get  to  it.  No  trouble 
is  experienced  with  the  valve  under  the  hood  of  a  touring 
car.  When  a  carbureter  is  used  where  water  or  dirt  are 
thrown  on  it,  the  manufacturers  furnish  a  gauze  cage  to  cover 
and  protect  it. 

Float  Feed  Mechanism — When  the  fuel  is  at  the  proper  level 


114 


MOTORS  AND  MECHANISM 


the  gasolene  inlet  valve  is  held  down  to  its  seat  by  its  own 
weight  and  the  spring  closes  the  supply,  the  float  being  clear 
of  the  float  lever.  As  soon  as  the  level  drops  the  float  drops 
with  it,  and  resting  its  weight  on  the  long  end  of  the  float  lever 
pushes  it  down  and  lifts  the  short  end  which  lifts  the  gaso- 
lene inlet  valve  and  admits  more  fuel  till  the  float  rises  clear 
of  the  lever  again.  .To  raise  the  fuel  level  adjust  the  nuts  on 
the  gasolene  inlet  valye  nearer  the  point  of  the  valve ;  to  lower 
it,  set  them  further  away.  Lock  them  tight  after  the  adjust- 
ment is  made.  The  distance  from  the  bottom  edge  of  the  ad- 
justing nut  to  the  point  of  the  gasolene  inlet  valve  averages 


PLOAT 


TO  PRIME  THE 
CARBURETER 
LIFT  UP  THIS 
STEM 


FLOAT  LEVEL 
ADJUSTING  NUTS 


GASOLINE  INLET 
VALVE  SEAT 


The  Breeze  Carbureter — Float  Feed  Mechanism. 

about  5-16  of  an  inch  on  a  properly  adjusted  carbureter.  Don't 
change  the  tension  of  the  spring.  The  fuel  level  must  be 
properly  adjusted  on  any  float  feed  carbureter.  The  correct 
point  is  usually  about  1-16  inch  below  the  tip  of  the  spray 
nozzle.  For  an  engine  with  short  inlet  pipe  of  large  diameter 
the  level  may  be  set  a  little  lower.  Keep  the  level  as  low  as 
possible.  A  high  fuel  level  wastes  fuel  and  causes  an  engine 
to  heat  up. 

Adjustment  of  the  Breeze  Carbureter — Adjustments  can  al- 
ways be  best  made  with  the  muffler  cut  out  or  better  still  the 
*xhaust  pipes  taken  off  so  that  the  exhaust  from  each  cylinder 


MOTORS  AND  MECHANISM  115 

may  be  observed.  If  the  ignition  is  right  and  the  compression 
and  valve  setting  the  same  on  all  cylinders  the  exhausts  should 
all  be  the  same  color.  The  blue  flame  exhaust  is  not  the  best 
for  power,  the  mixture  is  too  rich.  The  purple  flame  is  the 
correct  color.  A  yellow  color  shows  too  weak  a  mixture ; 
black  smoke,  too  much  fuel.  Too  much  oil  makes  the  color 
red. 

From  three-quarters  of  a  turn  to  a  turn  and  a  quarter  is 
the  usual  opening  of  the  needle  valve  required.  Screwed  all 
the  way  down  it  is  closed.  To  open  it  turn  backward.  The 
correct  position  can  only  be  determined  by  experiment.  With 


Gauze  Cage  for  Exposed  Carbureters. 

the  throttle  and  spark  stationary,  the  correct  position  for  the 
needle  valve  is  that  at  which  the  engine  runs  fastest. 

Set  the  needle  valve  first  for  low  speeds  with  the  throttle 
nearly  closed  and  the  spark  on  center.  Then  advance  the 
spark  and  open  the  throttle  and  adjust  for  high  speeds  by 
tightening  or  loosening  the  tension  of  the  auxiliary  air  valve 
spring. 

Backfiring  is  caused  by  too  weak  an  air-valve  spring,  dirt 
in  the  carbureter,  or  an  insufficient  flow  to  the  carbureter.  If 
the  auxiliary  air  valve  spring  has  to  be  weak,  a  small  stran- 
gling tube  may  be  used  around  the  spray  nozzle  and  a  large 
one  where  the  auxiliary  air  valve  spring  has  to  be  very  strong. 
A  particularly  strong  spring  has  to  be  used  with  engines  of 
the  valve-in-the-head  and  "T"  head  types. 


116 


MOTORS  AND  MECHANISM 


Carbureter  Troubles. 

The  following  remarks,  for  which  we  are  indebted  to  "Car- 
bureters and  Engine  Troubles,"  published  by  the  Breeze  Car- 
bureter Company,  apply  to  almost  all  float  feed  carbureters. 

Air  valve  springs  shorten  slightly  after  long  use,  and  ad- 
justment is  provided  to  take  up  the  tension.  Imported  steel 
wire  for  springs,  copper  plated  to  prevent  rust,  stand  up 
longer  than  the  cheap  brass  wire  frequently  used. 

Dirt  getting  into  the  spray  nozzle  causes  backfiring  in  the 


The  Breeze  Fuel  Strainer. 

carbureter,  and  while  the  engine  runs  very  fast  and  free  on 
starting  it  will  stop  when  the  clutch  is  thrown  in.  The  dirt 
can  generally  be  got  rid  of  by  opening  the  gasolene  adjust- 
ment a  full  turn  wh-ile  the  engine  is  running;  it  is  sucked  clear 
through  the  spray  nozzle.  Sometimes  a  larger  piece  of  dirt 
gets  in  and  acts  as  a  valve,  stopping  up  the  nozzle  when  the 
throttle  is  opened.  The  only  plan  in  this  case  is  to  take  off  the 
base  and  clean  out  the  fuel  passages.  Don't  go  to  this  trouble 
till  you  are  sure  that  your  battery  is  not  weak.  The  symp- 
toms are  often  the  same. 

Irregular  running  of  the  engine  may  be  caused  by  dirt  in 


MOTORS  AND  MECHANISM  1.17 

the  carbureter,  sticking  float  lever  or  fuel  valve,  and  very  often 
by  a  nearly  broken  battery  wire,  dirty  commutator  or  sticking 
coil  trembler.  Speeding  up  and  slowing  down  under  load  are 
generally  caused  by  too  small  a  fuel  pipe,  insufficient  head 
to  the  fuel,  or  dirt  or  water. 

Overheating  of  the  engine  may  be  caused  by  many  things, 
as  insufficient  water  circulation,  improper  timing  or  insuffi- 
cient lift  to  exhaust  valves.  Either  too  weak  or  too  rich  a 
mixture  burns  slowly  and  gives  up  a  larger  proportion  of  heat 
to  the  cylinder  head  and  wall  than  a  perfect  mixture  does.  A 
poor  spray  overheats,  so  does  poor  oil. 

Often  when  a  new  carbureter  is  fitted  to  a  car  that  has  been 
used  the  complaint  is  made  that  as  soon  as  the  throttle  is 
opened  the  engine  pounds  and  knocks  and  that, the  symptoms 
are  worse  than  before.  Very  li'kely.  The  new  carbureter 
probably  gives  more  gas  and  power  than  the  old  one,  and  of 
course  when  combustion  chambers  and  piston  heads  are  car- 
bonized from  poor  oil  or  bad  mixture,  the  more  gas  you  put 
in  the  cylinder  the  worse  the  knock.  Take  off  the  cylinder 
heads  and  soak  them  over  night  in  kerosene,  clean  them 
thoroughly,  and  piston  heads  too,  and  don't  neglect  the  valve 
passages.  It  is  not  so  much  the  even  deposit  as  the  little 
lumps  that  stick  up  that  cause  the  trouble. 

Commutators  or  unevenly  timed  tremblers  on  coils  some- 
times cause  trouble.  The  explosions  must  take  place  in  each 
cylinder  when  the  piston  is  in  the  same  position.  If  any 
cylinder  is  timed  too  early  there  will  be  loss  of  power,  knock- 
ing", overheating  and  possibly  a  broken  crankshaft  and  always 
a  quicker  wearing  out  of  wrist  pin  and  crank  pin  bearings. 
A  wabbly  commutator  makes  the  same  trouble. 

Missing  in  one  cylinder  may  be  caused  by  that  cylinder -hav- 
ing a  leak  around  the  valve  or  valve  cage  seats,  by  the  inlet 
valve  opening  too  much  and  not  closing  as  quickly  as  the 
others,  or  by  a  valve  not  seating  at  all ;  or,  by  that  cylinder 
being  carbonized.  These  things  cause  the  engine  to  take  a 
dl  Cerent  mixture.  If  the  cylinders  are  right  the  same  car- 
b  Veter  adjustment  will  suit  all. 


118  MOTORS  AND  MECHANISM 

Flooding — Suppose  when  you  turn  on  the  gasolene  or  stop 
your  engine  there  is  a  persistent  dropping  of  gasolene  from 
the  bottom  of  the  carbureter.  It  must  be  stopped,  fuel  is  being 
wasted  and  the  mixture  spoiled  on  low  speeds. 

Don't  start  in  to  change  the  fuel  level  till  you  are  absolutely 
sure  it  is  wrong.  Flooding  when  caused  by  dirt  under  the  fuel 
valve  can  often  be  stopped  by  lifting  the  fuel  inlet  valve  and 
letting  the  dirt  flush  through.  If  this  does  not  stop  it  the 
level  is  most  likely  too  high. 

Before  readjusting  the  float  level  you  might  take  off  the 
base  and  take  out  the  float  and  shake  it  and  listen  for  liquid 
inside ;  a  leak,  though  very  rare,  is  possible,  and  will  permit 
gasolene  to  get  inside  and  lessen  the  float's  buoyancy.  Write 
or  wire  for  a  new  one  and  then  return  the  leaky  one  for  repairs. 
A  temporary  repair  can  often  be  effected  by  drying  out  the 
gasolene  and  painting  a  little  shellac  over  the  leak.  Don't 
mistake  loose  solder  in  the  float  for  gasolene. 

Having  tested  these  points  if  the  trouble  is  not  there,  the 
fuel  level  is  too  high  and  must  be  adjusted.  Shut  off  the  fuel 
every  time  you  put  away  a  car.  It  is  safest,  because  there  is 
no  float  feed  mechanism  that  can  always  be  trusted  abso- 
lutely, and  besides  this  the  lighter  part  of  the  fuel  keeps  evapo- 
rating till  the  bowl  of  the  carbureter  is  full  of  too  heavy  a 
liquid  to  make  starting  next  morning  as  easy  as  it  might  be. 
Always  have  two  shut-off  cocks  in  your  gasolene  line,  one  at 
the  carbureter  or  where  you  can  get  at  it  easily,  and  the  other 
close  to  the  tank,  in  case  the  pipe  breaks.  Either  may  save  the 
car  some  day. 

Carbureter  Cautions. 

Don't  try  and  start  with  the  throttle  entirely  closed. 

Gasolene  valves  have  been  known  to  jar  shut. 

Remember  that  "Carbureter  knock"  may  be  found  in  a  loose 
fly-wheel,  in  loose  electrical  connections  or  commutators  that 
ground  sometimes  in  the  wrong  place. 

Don't  adjust  the  carbureter  as  soon  as  the  engine  works 
badly.  There  are  such  things  as  clogged  feed  pipes,  poor 
ignition,  and  exhaust  valves  that  don't  seat  properly. 


MOTORS  AND  MECHANISM  119 

Flooding  seldom  means  readjustment  of  float  feed  mechan- 
ism. Usually  there  is  dirt  under  the  gasolene  valve  seat  or, 
very  rarely,  a  leaky  float. 

Don'tv  forget  that  automatic  inlet  valves  must  have  a  very 
short  lift,  and  when  the  engine  has  more  than  one  cylinder,  the 
springs  in  these  valves  must  be  of  an  even  tension.  If  these 
springs  are  weak  or  have  too  much  lift,  part  of  the  gas  will  be 
blown  backwards  through  the  carbureter  in  the  compression 
stroke. 

Don't  monkey  with  any  carbureter  till  you  have  read  the 
maker's  book.  You  may  know  more  about  it  than  he,  but  you 
might  as  well  get  his  ideas  on  the  subject. 


Stewart  Vacuum  Fuel  Feed. 

There  are  many  disadvantages  connected  with  both  the 
gravity  and  pressure  systems  of  gasolene  supply.  With  the 
gravity  system  it  is  always  difficult  to  get  a  sufficient  height 
of  liquid  above  the  carbureter,  particularly  when  ascending 
or  descending  heavy  grades.  To  get  the  maximum  height  of 
tank  over  carbureter  it  is  necessary  to  place  both  the  tank 
and  carbureter  in  inaccessible  places,  the  tank  under  the  seat 
or  cowl,  and  the  carbureter  low  down  in  the  hood  between 
the  chassis  and  the  engine.  With  the  tank  under  the  seat  it 
is  necessary  to  disturb  the  occupants  of  the  front  seat  when 
refilling. 

When  the  carbureter  is  located  at  a  low  point  in  the  chassis 
it  necessitates  the  use  of  a  long  intake  pipe  which  affects 
the  quality  of  the  mixture  to  a  great  extent,  especially  in 
cold  weather. 

With  the  pressure  system  an  absolutely  tight  tank  is  re- 
quired. Leakage  in  the  upper  part  of  the  tank  or  above  the 
fuel  level  will  reduce  the  feed  of  gasolene  at  the  carbureter  if 
it  exceeds  the  capacity  of  the  pump  or  reducing  valve.  Ex- 
cessive pressure  will  flood  the  carbureter  unless  an  auxiliary 
tank  is  indulged  in,  and  the  overflow  from  the  carbureter 


120 


MOTORS  AND  MECHANISM 


greatly  increases  the  danger  of  fire  to  say  nothing  of  its  effect 
upon  the  mixture. 

In  the  vacuum  system,  the  suction  of  the  motor  is  utilized 
in  lifting  the  gasolene  from  the  main  tank  to  the  carbureter, 


'GASOLINE 


FIG.  4.— STEWART  VACUUM  FUEL  SYSTEM. 

the  suction  being  obtained  from  a  connection  to  the  intake 
manifold.  As  will  be  seen  from  the  accompanying  figure,  this 
device  consists  of  a  vertical  tank  which  is  divided  into  two 
compartments  by  a  "horizontal  partition  X.  The  tank  is  usu- 


MOTORS  AND  MECHANISM  121 

ally  mounted  on  the  front  of  the  dash  and  under  the  hood  at 
a  considerable  height  above  the  carbureter.  Being  close  to 
the  motor  there  is  very  little  variation  between  the  upper 
and  lower  levels  when  the  car  is  climbing  hills. 

A  metal  float  A  is  placed  in  the  upper  chamber  which  main- 
tains a  constant  level  through  the  lever  system  and  the  valves 
F-I-J  and  D.  The  pipe  H  connected  to  the  motor  intake  mani- 
fold produces  a  vacuum  in  the  upper  compartment  or  fills 
chamber  when  the  float  A  allows  the  valve  I  to  open,  with  the 
atmospheric  valve  J  closed.  With  a  vacuum  in  the  space  and 
the  gasolene  valve  F  open,  the  gasolene  is  drawn  from  the 
supply  tank  through  the  feed  pipe  E  and  valve  F  into  the 
upper  compartment. 

When  the  required  level  is  reached,  the  float  A  closes  the 
fuel  valve  F  and  the  suction  valve  I,  and  opens  the  atmos- 
pheric valve  J  which  allows  air  to  enter  the  tank  and  break 
the  vacuum.  As  the  float  in  rising  has  by  this  time  opened 
the  valve  D  in  the  partition,  the  lack  of  vacuum  in  the  upper 
chamber  allows  the  gasolene  to  flow  into  the  lower  chamber 
through  C.  The  vacuum  which  up  to  this  time  had  been  sup- 
porting the  liquid  column  in  the  upper  compartment  is  broken 
by  the  air  entering  through  the  pipe  G  and  valve  J.  The  lower 
chamber  is  kept  at  atmospheric  pressure  at  all  times  by  air 
entering  through -the  pipes  B  and  G  which  pass  above  the 
valve  J. 

Gasolene  is  fed  to  the  carbureter  from  the  lower  chamber 
through  the  pipe  K  by  gravity.  The  flap  valve  C  between 
the  two  chambers  prevents  the  vacuum  from  drawing  the 
gasolene  in  the  lower  chamber  into  the  upper  chamber  when 
the  valve  D  is  lifted  off  the  seat.  When  the  lower  chamber 
is  filled  the  action  is  again  repeated,  0.05  gallon  being  trans- 
ferred from  the  main  tank  at  each  operation.  The  action  of 
the  valves  must  be  intermittent  so  that  atmospheric  pressure 
can  be  maintained  a  part  of  the  time. 


122  MOTORS  AND  MECHANISM 

A  drain  plug  L  allows  the  water  and  dirt  collected  at  the 
bottom  of  the  tank  to  be  drawn  off,  the  upper  extension  of  the 
pipe  K  preventing  foreign  matter  from  entering  the  carbu- 
reter. If  the  car  has  been  standing  empty  for  a  time  or  when 
it  is  desired  to  fill  it  the  first  time,  the  motor  is  cranked  over 
four  or  five  times  with  the  throttle  closed.  This  will  produce 
enough  vacuum  to  supply  the  carbureter  for  starting. 

When  the  vacuum  system  is  used,  a  tube  E  runs  to  the 
bottom  of  the  main  tank.  A  small  vent  must  be  provided  in 
the  main  tank  to  allow  the  gasolene  to  flow  freely  to  the  pipe. 
CARBURETER  ADJUSTMENTS. 

The  Holley  Carbureter. 

In  the  illustration  of  the  Holley  carbureter  the  adjustable 
gasolene  needle  is  shown  (L).  The  air  enters  at  A  and  passes 


The  Holley  Carbureter,  Model  "W." 

down  and  up  through  a  U-shaped  mixing  tube.  The  gaso- 
lene enters  from  the  float  chamber  by  an  orifice  controlled 
by  the  adjustable  needle.  The  normal  gasolene  level  is  3/32 
inch  above  the  bottom  of  the  U-shaped  passage,  so  that  a 
puddle  is  formed.  Here  the  air  passage  is  restricted,  increas-. 
ing  the  velocity  of  the  stream.  As  the  motor  speed  increases, 
the  puddle  is  gradually  swept  away  and  its  area  diminished, 
preventing  the  formation  of  an  over-rich  mixture.  At  the 


MOTORS  AND  MECHANISM  123 

highest  speeds  the  puddle  is  wiped  out  and  an  ordinary  spray 
takes  its  place.     An  overflow  device  prevents  flooding. 

In  operation  the  gasolene  needle  is  adjusted  to  a  point 
where  the  motor  runs  best,  with  throttle  wide  open  and  spark 
about  center.  Next  close  the  throttle  to  where  the  motor 
runs  slow  enough  to  suit.  If  the  motor  will  not  run  slow,  it 
indicates  lack  of  gasolene  because  of  too  low  level.  If  motor 
runs  slow  enough  with  throttle  partly  closed,  but  misses  upon 
opening  throttle,  it  indicates  too  high  a  gasolene  level.  To 
change  the  level  remove  the  gasolene  inlet  needle  guide  cap 
T  and  take  out  the  gasolene  inlet  needle.  Hold  the  weight 
M  by  its  flat  sides  (so  as  not  to  mar  it  and  cause  it  to  stick) 
and  loosen  the  taper  locknut  O.  Then  by  screwing  the  needle 
into  the  weight  M  the  gasolene  level  is  raised  in  the  float 
chamber;  by  unscrewing  these  parts,  the  level  is  lowered. 
One  turn  of  the  needle  L  in  the  weight  M  changes  the  gaso- 
lene level  about  3/32  inch;  one  half  turn  about  half,  etc. 
When  level  is  where  desired  tighten  locknut  O.  Normal 
level  should  show  puddle  about  3/32  inch  deep  when  motor 
is  not  running.  Conditions  may  demand  this  to  be  altered 
slightly.  R  is  a  sediment  plug  and  has  nothing  to  do  with 
adjustment. 

The  Schebler  Carbureter. 

In  the  Schebler  carbureter,  of  which  we  illustrate  several 
models,  when  the  motor  is  running  at  its  minimum  speed, 
the  air  is  drawn  through  an  aperture  of  fixed  dimensions. 
As  the  speed  is  increased,  and  consequently  the  flow  of  gaso- 
lene becomes  greater,  more  air  is  needed  and  this  additional 
supply  is  furnished  by  the  compensating  air  valve  A  (see 
illustration  of  Schebler  Model  D),  which  opens  more  and 
more  as  the  speed  of  the  engine  increases.  The  compensat- 
ing air  valve,  when  once  adjusted,  admits  a  regulated  supply 
of  air  in  accordance  with  the  degree  of  vacuum  produced  by 
the  piston  of  the  motor.  In  adjusting,  the  needle  valve  E 
should  be  first  closed,  and  then  opened  about  from  five-eighths 
to  three-quarters  of  a  turn.  Retard  the  spark,  open  the  throt- 
tle P  about  one-fourth,  so  as  to  equalize  the  fixed  air  open- 


124 


MOTORS  AND  MECHANISM 


ing  below  the  compensating  air  valve  A.  Start  the  motor 
and  adjust  the  needle  valve  E  until  the  motor  runs  smoothly 
and  without  back  firing  or  missing.  Now  open  the  throttle 
P  wide,  keeping  the  spark  retarded,  and  by  turning  the  air 
valve  adjusting  screw  M  increase  or  weaken  the  tension  on  the 


The  Schebler  Carbureter — Model  D — Section. 


A  Compensating  air  valve 

B  Float  chamber 

C  Mixing  chamber 

D  Spraying  nozzle 

E  Needle  valve 

F  Float 

G  Reversible  union 

H  Float  valve 

I    Float  connection 

J    Float  hinge 

K  Throttle 


L  Float  chamber  cover 

M  Air  valve  adjusting  screw 

N  Cork  gasket 

O  Air  valve  spring 

P  Throttle  lever 

R  Pipe  connection 

S   Throttle  stop 

T  Drain  cock 

U  Float  valve  cap 

V  Flushing  pin 


air  valve  spring  O  until  the  proper  mixture  is  obtained.  If  the 
mixture  is  too  rich,  the  tension  of  the  spring  O  should  be 
weakened,  permitting  more  air  to  enter  the  carbufeter; 
should  the  mixture  be  too  weak,  the  tension  of  the  spring 
should  be  increased. 


MOTORS  AND  MECHANISM 


125 


Schebler  carbureters  are  made  of  brass,  but  aluminum  is 
furnished  on  special  orders.  The  bowl  design  combines  com- 
pactness with  practicability,  serving  for  reservoir  as  well  as 
having  the  float  chamber  embodied  therein.  The  float  is 
made  of  cork,  heavily  shellaced  and  hinged  as  shown  in  the 
sectional  view,  letter  J.  The  size  of  the  gasolene  valve  is 
much  larger  than  ordinarily  used.  Gasolene  .  is  supplied 
through  a  reversible  union  which  permits  the  feed  pipe  to 
run  in  any  direction  desired. 

The  Stromberg  Carbureters. 

Many  well-known  machines  are  fitted  with  the  Stromberg 
type  carbureters,  of  which  we  illustrate  two  examples  in  sec- 
tion, namely  Types  A  and  B. 


Stromberg  Carbureter— Type  A — Section. 

The  following  are  the  methods  of  adjusting  these  carbur- 
eters : 

How  to  Adjust  Stromberg  Type  A. — After  the  carbureter 
is  installed  turn  on  the  gasolene,  and  note  if  the  level  of  the 
gasolene  in  Nthe  float  chamber  is  opposite  the  mark  or  line 
cut  on  the  outside  of  water  jacket  opposite  float  chamber. 
By  turning  the  adjusting  nut  D-i  up  or  down  you  can  raise 
or  lower  the  gasolene  level  so  that  it  will  be  opposite  the 


126  -       MOTORS  AND  MECHANISM 

line.  Do  this  before  starting  the  engine.  Next  see  that  the 
valve  V  seats  lightly  by  tapping  the  nut  V-5  lightly  with  the 
forefinger.  If  it  does  not  seat,  turn  up  adjusting  lock  V-i,  or 
if  too  tight,  .turn  down  V-i.  See  that  adjusting  locknut  V-3 
is  turned  down  as-  low  as  possible.  Next  prime  the  motor 
by  lifting  the  needle  valve  B  until  float  chamber  is  filled. 
You  will  notice  that  gasolene  drops  into  the  adjustable  air 
cup  F.  This  cup  should  be  adjusted  in  this  manner:  Turn 
up  the  air  cup  F  until  it  is  tight,  then  turn  it  down  one  or  two 
turns,  possibly  three,  according  to  the  motor.  On  the  av- 
erage motor  this  will  admit  the  proper  amount  of  air  which 
regulates  the  gasolene  supply.  If  you  are  getting  too  much 
gasolene,  turn  the  cup  up,  if  too  little,  turn  it  down. 

Next  start  the  motor  and  adjust  -the  low,  speed  adjusting 
nut  V-i  with  both  the  throttle  and  the  spark  retarded.  The 
spring  S-i  is  us.ed  to  seat  the  valve  V,  and  if  the  mixture  is 
too  rare  and  engine  back  fires,  turn  up  nut  V-i  until  the 
motor  runs  smoothly.  Next  advance  the  spark  and  open  the 
throttle  gradually  until  it  is  wide  open,  and  if  the  motor 
back  fires,  turn  tip  the  high  speed  adjusting  nut  V-3  one  notch 
at  a  time  until  the  motor  runs  smoothly  without  back  firing. 
Remember  that  the  valve  spring  S  simply  controls  the  valve 
V  on  open  throttle  or  high  speed,  and  should  not  be  in  con- 
tact with  nut  V-5  when  motor  is  at  rest.  The  seating  of 
valve  V  is  entirely  controlled  by  spring  S-i.  There  should 
be  a  space  between  the  nut  V-5  and  spring  S  of  about  1-32 
inch  and  not  over  1-8  inch,  according  to  the  motor. 

In  very  hot  weather  shut  the  water  off  when  the  carbureter 
gets  too  hot.  If  the  water  is  drawn  from  the  radiator  of  the 
car,  either  to  clean  same  or  in  laying  car  up  for  the  winter, 
be  sure  and  disconnect  the  water  pipe  connections  to  the 
water  jacket  on  the  carbureter  at  J-2,  so  that  the  water 
jacket  will  also  be  drained.  It  may  be  that  in  adjusting  the 
nut  V-3,  which  is  called  the  high-speed  adjusting  nut,  to  stop 
motor  back  firing  you  will  have  to  turn  up  nut  V-i  one  or 
two  notches,  but  after  doing  so  be  sure  to  see  that  the  motor 
runs  smoothly  on  closed  throttle. 


.    MOTORS  AND  MECHANISM  127 

The  motor  uses  just  enough  gasolene  to  keep  it  going  on 
low  speed,  and  as  it  increases  in  speed  it  takes  automatically 
the  quantity  of  gasolene  which  is  necessary.  The  suction 
created  by  the  motor  draws  air  in  through  the  fixed  air  open- 
ing between  the  adjustable  air  cup  F  and  the  bottom  of  the 
water  jacket  passes  up  through  the  mixing  chamber  L  past 
the  spraying  nozzle  H  and  in  passing  sucks  the  gasolene 
out  of  the  nozzle  in  a  canopy-shaped  spray.  This  mixture 
is  then  joined  by  the  air  coming  through  the  valve  V,  which 
creates  a  perfect  mixture.  The  more  air  that  comes  in  through 
the  adjustable  air  cup  and  the  less  through  the  valve  the 
richer  the  mixture  will  be  and  vice  versa,  so  do  not  have  your 
spring  S-i  too  tight. 

How  to  Find  Proper  Nozzle  Size — If  after  you  have  ad- 
justed the  auxiliary  air  valve  according  to  instructions,  the 
mixture  is  still  too  rich,  adjust  valve  V  until  it  is  off  its  seat, 
then  adjust  locknut  V-3  down  as  far  as  it  will  go,  and  if  the 
mixture  is  still  too  rich,  it  is  conclusive  proof  that  the  nozzle 
in  the  carbureter  is  too  large.  If  the  motor  misses  on  high 
speed  on  normal  adjustments,  tighten  up  on  valve  V  by  turn- 
ing up  the  nut  V~3  and  nut  V-i.  If  these  springs  are  then 
too  tight  to  get  proper  mixture,  put  in  a  smaller  nozzle.  To 
change  the  nozzle  H,  remove  the  plug  G,  then  take  out  noz- 
zle with  an  ordinary  screwdriver. 

How  to  Adjust  Stromberg  Type  B — Type  B  differs  from 
Type  A  in  being  made  without  the  water  jacket  and  is  con- 
centric, having  the  float  chamber  built  around  the  mixing 
chamber. 

After  the  carbureter  is  installed  turn  on  the  gasolene,  and 
note  if  the  level  of  the  gasolene  in  the  float  chamber  is  15-16 
inch  from  the  rim  on  the  bottom  which  holds  the  glass.  By 
turning  the  adjusting  nut  M  up  or  'down  you  can  raise  or 
lower  the  gasolene  level.  See  that  the  level  is  right  before 
starting  the  engine.  Next  see  that  valve  V  seats  lightly  by 
tapping  the  nut  E  lightly  with  the  forefinger.  If  it  does  not 
seat  turn  up  adjusting  nut  K,  or  if  too  tight,  turn  down  K. 
See  that  adjusting  locknut  H  is  turned  down  as  low  as  pos- 


128 


MOTORS  AND  MECHANISM 


sible.  Next  prime  the  motor  by  lifting  needle  valve  O  until 
float  chamber  is  filled.  You  will  notice  that  gasolene  drops  into 
the  adjustable  air  cup  C.  This  cup  should  be  adjusted  in  this- 
manner:  Turn  up  the  air  cup  C  until  it  is  tight,  then  turn 
it  down  two  full  turns.  On  the  average  motor  this  will  ad- 
mit the  proper  amount  of  air  which  regulates  the  gasolene 
supply.  If  you  are  getting  too  much  gasolene,  turn  the  cup 
Up,  if  too  little,  turn  it  down.  Next  Ltart  the  motor  and  ad- 
just the  low-speed  adjusting  nut  K  with  both  the  throttle 
and  the  spark  retarded.  The  spring  S  is  used  to  seat  the 


Stromberg  Carbureter — Type  B — Section. 

valve  V,  and  if  the  mixture  is  too  rare  and  engine  back  fires, 
turn  up  nut  K  until  the  motor  runs  smoothly.  Next  advance 
the  spark  and  open  the  throttle  gradually  until  it  is  wide  open, 
and  if  the  motor  back  fires,  turn  up  the  high-speed  adjusting 
nut  H  one  notch  at  a  time  until  the  motor  runs  without  back 
firing.  Remember  that  the  valve  spring  R  simply  controls 
the  valve  V  on  open  throttle  or  high  speed,  and  should  not 
be  in  contact  with  nut  E  when  motor  is  at  rest.  The  seating 
of  valve  V  is  entirely  controlled  by  spring  S.  There  should, 
be  a  space  between  the  nut  E  and  spring  R  of  about  1-32  inch 
and  not  over  1-8  inch  according  to  the  motor.  It  may  be  that 
in  adjusting  the  nut  II,  which  is  called  the  high-speed  ad- 


MOTORS  AND  MECHANISM  129 

justing  nut,  to  stop  motor  back  firing  you  will  have  to  turn 
up  nut  K  one  or  two  notches,  but  after  doing  this  be  sure  to 
see  that  the  motor  runs  smoothly  on  closed  throttle. 

The  motor  uses  just  enough  gasolene  to  keep  it  going  on 
low  speed,  and  as  it  increases  in  speed  it  takes  automatically 
the  quantity  of  gasolene  which  is  necessary.  The  suction 
created  by  the  motor  draws  air  in  through  the  fixed  air  open- 
ing between  the  adjustable  air  cup  C,  and  the  bottom  of  the 
gasolene  chamber,  passes  up  through  the  mixing  chamber  A 
past  the  spraying  nozzle  D,  and  in  passing  sucks  the  gaso- 
lene out  of  the  nozzle  in  a  canopy-shaped  spray.  This  mix- 
ture is  then  joined  by  the  air  coming  through  the  valve  V, 
which  produces  a  perfect  mixture.  The  more  air  that  comes 
in  through  the  adjustable  air  cup,  and  the  less  through  the 
valve  the  richer  the  mixture  will  be  and  vice  versa,  so  do  not 
have  your  spring  S  too  tight.  To  change  the  nozzle^  D,  re- 
move the  drain  cock,  then  take  out  nozzle  with  screwdriver. 

Carbureter,  Alcohol — Carbureters  for  the  use  of  denatured 
alcohol  instead  of  gasolene  in  internal  combustion  engines 
are  now  successfully  in  operation.  Experiments  have  also 
been  made  in  the  use  of  alcohol  with  acetylene.  In  this  case 
the  alcohol  mixture  is  passed  through  a  wire  gauze  containing 
calcium  carbide  and  the  water  contained  in  the  mixture  acts 
upon  the  carbide  and  produces  acetylene  gas.  Another  type 
of  alchohol  carbureter  is  used  with  alcohol  and  gasolene,  the 
engine  being  started  with  gasolene  and  running  with  alcohol 
as  soon  as  the  carbureter  is  sufficiently  heated.  Heat  is 
invariably  required  for  the  complete  vaporization  of  alcohol. 


130  MOTORS  AND  MECHANISM 


CHAPTER  VIII 
DRIVING  FORD  CARS  AND  TRUCKS 

Probably  one  of  the  most  important  features  of  running  a. 
Ford  car  is  that  of  fuel  economy,  and  with  this  idea  in  view 
will  take  up  the  subject  of  carbureter  adjustments  before 
entering  into  the  other  items,  such  as  ignition,  that  contribute 
so  greatly  to  the  efficiency  of  the  car."  As  with  any  other 
car,  the  greatest  fuel  efficiency  is  attained  by  properly  mixing 
and  proportioning  the  gasolene  vapor  and  air  for  any  particu- 
lar load  or  atmospheric  condition. 

When  the  Ford  is  equipped  with  a  Holley  carbureter,  the 
only  point  of  adjustment  is  that  of  the  needle  valve  that  con- 
trols the  flow  through  the  spraying  nozzle.  This  must  be 
adjusted,  of  course,  so  that  the  amount  of  gasolene  passed  is 
just  as  little  as  will  meet  the  power  requirements  at  that  par- 
ticular moment.  As  this  maximum  amount  of  power  varies 
from  time  to  time  owing  to  differences  in  grades  and  road 
conditions,  it  is  evident  that  the  mixture  would  have  to  be 
adjusted  continually  for  the  most  economical  results.  Unfor- 
tunately such  continuous  adjustment  is  practically  impossible 
so  that  the  best  we  can  do  is  to  effect  a  compromise  between 
the  maximum  and  minimum  demands  for  normal  running  and 
make  the  temporary  adjustment  when  striking  a  steep  grade 
or  heavy  road.  Owing  to  the  method  of  installing  the  carbu- 
reter control,  the  adjustment  of  the  needle  valve  for  varying 
conditions  is  not  as  difficult  as  the  foregoing  might  lead  one 
to  believe,  and  very  good  results  may  be  obtained  with  but 
comparatively  little  attention. 

A  long  rod  leading  from  the  carbureter  nozzle  valve  to  the 


MOTORS  AND  MECHANISM  131 

dashboard  terminates  in  a  brass  button  within  reach  of  the 
driver's  side  of  the  dashboard.  By  turning  the  button  in  one 
direction  or  the  other  it  is  possible  to  open  or  close  the 
needle  valve  and  vary  the  amount  of  gasolene.  The  gasolene 
valve  button  should  be  turned  clockwise  as  far  as  possible 
(closing  needle  valve)  without  loss  of  power,  since  this  gives 
the  most  dilute  mixture  possible.  The  position  marked  by 
the  maker  for  the  normal  driving  position  is  really  the  posi- 
tion for  maximum  engine  power  and  is  therefore  not  the 
proper  one  for  level  road  driving,  since  under  the  latter  condi- 
tions the 'mixture  is  by  far  too  rich.  To  facilitate  frequent 
changes  in  the  mixture  several  devices  have  been  placed  on 
the  market  which  bring  the  control  from  its  present  awkward 
position  to  a  point  either  on  the  steering  wheel  or  near  at 
hand.  This  is  a  great  convenience  and  is  well  worth  install- 
ing, since  by  manipulating  through  one  of  these  attachments, 
several  owners  have  obtained  as  high  as  40  miles  per  gallon. 

With  the  mixture  too  weak,  the  engine  will  lose  speed  and 
power,  this  being  generally  accompanied  by  carbureter  "pop- 
ping"  or  firing  back  through  the  carbureter  inlet.  This  is  not 
only  disagreeable,  but  is  dangerous,  since  the  discharge 
through  the  carbureter  is  liable  to  set  fire  to  the  car,  especially 
if  the  carbureter  drips  or  overflows  to  any  extent.  Back-fir- 
ing can  be  cured  by  opening  the  needle  valve  to  increase  the 
richness  of  the  mixture.  An  overly  advanced  spark  will  also 
cause  back-firing  occasionally  with  a  proper  mixture,  so  that 
if  the  correction  in  mixture  does  not  stop  the  trouble,  try 
readjusting  the  spark. 

In  regard  to  the  proper  running  point  for  the  spark  it  can 
be  said  that  the  most  economical  position  will  be  found  when 
advanced  just  short  of  the  position  in  which  knocking  begins. 
If  much  retarded  from  this  position,  the  engine  will  heat 
rapidly,  lose  power,  and  increase  the  fuel  consumption  for 
equal  speeds.  If  advanced  to,  and  held  on,  the  point  where 
knocking  continues,  there  will  be  rapid  wear  and  liability 
of  damage  to  the  bearings  and  crankshaft.  When  up  to 
required  speed  run  up  to  knocking  point,  and  then  slightly 


132  MOTORS  AND  MECHANISM 

retard  until  knocking  ceases.  For  other  points  in  regard  to 
the  Ford  ignition  system  consult  matter  under  the  heading, 
"Missing  and  Knocking." 

Starting  Ford  Motor. 

Starting  trouble  with  the  Ford  motor  may  be  caused  by 
a  poor  mixture,  ignition  trouble  or  by  trouble  within  the  motor 
proper,  but  with  a  car  in  fairly  good  condition  it  usually  can 
be  traced  to.  the  mixture.  At  least  this  should  be  the  point  on 
which  to  base  future  operations,  since  the  alterations  are  more 
easily  and  surely  made  with  the  carbureter  than  with  the 
ignition  system  or  motor. 

First  note  the  position  of  the  V-shaped  nick  on  the  nozzle 
adjustment  button  on  dash  at  which  the  motor  develops  its 
maximum  power  on  the  level.  Say  this  points  towards  the 
front  of  the  car.  With  a  cold  motor  turn  the  button  one-half 
revolution  toward  the  left,  open  the  throttle  to  about  the  20- 
mile  per  hour  position*  and  either  fully  retard  the  spark  or  place 
the  lever  within  two  or  three  notches  of  its  furtherest  back 
position.  Leave  switch  open,  and  turn  over  engine  4%  rev- 
olutions, the  valve  in  the  carbureter  intake  being  held  closed 
during  this  period  by  means  of  the  wire  control.  The  wire 
pulled  fully  out  will  fill  the  cylinders  with  a  rich  mixture 
due  to  the  heavy  suction  in  the  mixing  chamber.  Switch  on 
the  current,  let  go  of  the  intake  valve  wire,  and  give  a  quick 
up-turn  on  the  starting  handle.  This  should  fire  the  motor. 
If  motor  does  not  start  give  two  or  three  more  quick  up-pulls 
on  starting  crank,  without  using  the  air  inlet  valve  wire.  Too 
frequent  use  of  the  air  valve  is  likely  to  flood  motor  and  cause 
additional  delay.  If  motor  still  does  not  start  examine  the 
ignition  system,  especially  the  vibrators  on  the  spark  coil. 

With  the  engine  firing,  partially  close  the  throttle  valve 
lever  on  wheel,  and  slowly  turn  back  notch  on  nozzle  adjust- 
ment button  until  it  is  again  in  the  normal  running  position. 
When  starting  the  motor  it  is  a  safe  plan  to  put  on  the  brakes 
so  that  the  car  will  not  start  to  crawl  forward  when  the 


MOTORS  AND  MECHANISM  133 

engine  starts  through  the  stiffness  of  the  cold  oil  in  the  trans- 
mission. 

In  starting  a  warm  engine,  the  mixture  must  be  lean  rather 
than  rich,  this  requiring  a  different  adjustment  of  the  needle 
valve  button.  The  air  valve  wire  should  not  be  used,  as  the 
chances  are  that  the  mixture  is  already  too  rich.  Place  the 
nozzle  control  button  in  the  normal  running  position  (toward 
dash  in  above  example),  throw  in  switch  and  turn  engine 
over.  If  it  fails  to  start  firing,  turn  nozzle  button  about  one- 
half  revolution,  or  until  needle  valve  is  nearly  closed,  and 
pump  engine  over  several  revolutions  to  get  rid  of  the  rich 
gas,  the  switch  being  in  the  off  position.  Now  turn  needle 
valve  button  back  to  normal  running  position  once  more, 
close  switch,  and  give  short,  -sharp  pull  on  starting  crank. 
Engine  should  start. 

See  that  the  spark  coil  vibrator  blades  are  adjusted  as 
lightly  as  possible,  and  when  engine  is  running,  turn  off  con- 
tact screws  until  a  cylinder  stops  firing.  Now  run  screw  in 
again  until  motor  again  fires  and  give  an  additional  turn  of 
about  one-eighth  revolution.  See  special  note  for  other  igni- 
tion adjustments. 

Before  turning  the  motor  over  be  sure  that  the  spark  is 
well  retarded,  despite  the  fact  that  almost  any  engine  starts 
better  with  the  spark  advanced.  A  savage  back-kick  from 
the  starting  handle  due  to  an  advanced  spark  is  usually  very 
successful  in  mashing  the  small  bones  of  the  wrist  and  is 
capable  of  even  more  severe  and  lasting  injury.  An  acquaint- 
ance of  the  writer  was  jerked  down  suddenly  by  his  starting 
crank  in  such  a  way  that  his  chin  struck  the  radiator  cap. 
As  he  happened  to  have  his  tongue  between  his  teeth  he  is 
now  minus  a  greater  part  of  that  useful  organ  of  speech  and 
can  also  exhibit  two  beautiful  five-tooth  bridges — upper  and 
lower.  Two  months  after  the  accident  he  had  the  plaster  cast 
removed  from  his.  right  wrist. 


134  MOTORS  AiVD  MECHANISM 

"Retard  When  Cranking." 

In  addition  to  the  dangers  mentioned  above,  an  advanced 
spark  is  likely  to  cause  back-firing  through  the  carbureter 
when  being  cranked.  This  is  due  to  the  motor  being  turned 
backward  so  that  the  burning  gas  in  the  cylinder  passes  out 
through  the  inlet  valve  and  into  the  carbureter.  If  the  car- 
bureter has  been  recently  flooded  or  if  the  float  valve  is 
leaky,  causing  the  gasolene  to  overflow,  there  .will  be  danger 
setting  fire  to  the  car.  Starting  a  cold  motor  with  a  weak 
mixture  often  causes  the  same  trouble. 

When  trouble  is  experienced  in  starting  the  motor  when  it 
is  hot  or  well  warmed  up,  the  cause  is  usually  due  to  a  rich 
mixture.  If  partially  closing  the  needle  valve  or  carbureter 
does  not  stop  the  trouble  it  is  likely  that  the  gasolene  level  is 
too  high  in  the  float  chamber  and  nozzle.  In  the  Model  "T" 
Ford,  the  gasolene  level  should  be  so  that  the  little  tube  inside 
the  carbureter  should  just  touch  the  gasolene  in  the  well. 

Ford  Speed  Changing. 

Speed  changing  on  the  Ford  is  accomplished  by  two  pedals 
and  a  side  lever,  a  third  pedal  located  on  the  footboard  being 
the  brake.  All  three  of  the  controls  act  directly  on  the  trans- 
mission sheaves  by  means  of  two  brake  bands  and  a  clutch. 
The  transmission  is  of  the  planetary  type  in  which  the  gears 
are  always  in  mesh,  the  first  speed  and  reverse  being  geared 
while  the  high  is  a  direct  driven  speed  produced  by  locking 
all  of  the  gears  into  a  unit  mass. 

To  obtain  the  first  speed,  the  clutch  pedal  "C"  is  pressed 
slightly  to  hold  the  gears  in  neutral  and  the  side  lever  is 
pushed  forward.  The  clutch  pedal  "C"  is  now  pushed  as  far 
forward  as  possible  and  is  held  there  until  the  car  accelerates 
on  the  first  speed  for  about  50  feet,  or  until  it  reaches  a  speed 
of  about  7  miles  per  hour.  It  is  now  thrown  into  second  speed 
or  "high"  by  releasing  the  clutch  pedal  and  allowing  it  to 


MOTORS  AND  MECHANISM  135 

return  the  entire  distance  toward  the  driver.  To  reverse,  it 
must  be  first  brought  to  a  stop,  and  the  side  lever  brought 
back  to  a  vertical  position.  By  depressing  the  reverse  pedal 
(R)  the  car  will  be  brought  into  reverse.  The  car  may  also 
be  reversed  by  depressing  the  clutch  pedal  (C)  half  way 
and  then  the  reverse  pedal  (R). 

For  first  and  second  speed,  the  lever  should  be  as  far  for- 
ward as  possible,  while  for  reverse  it  should  be  vertical. 

To  secure  a  smooth  change  with  the  Ford  transmission,  it 
is  necessary  after  speeding  up  on  first  gear,  say  to  6  miles 
per  hour,  to  close  the  throttle  as  the  foot  comes  back  into 
position  for  high  speed.  The  proper  condition  being  that  the 
engine  has  not  slowed  down  appreciably  when  the  high  speed 
clutch  engages  and  the  first  speed  band  disengages.  If  the 
throttle  is  closed  too  much,  there  will  be  a  jerk  due  to  the 
road  wheels  accelerating  the  engine.  If  the  throttle  is  not 
closed  enough,  there  will  be  a  jerk  due  to  the  engine  speed 
being  checked  by  the  application  of  the  clutch.  This  can  only 
be  perfected  by  practice.  A  worn  clutch  band  is  the  cause  of 
much  jerking  and  even  with  the  most  careful  manipulation  of 
pedal  and  throttle  it  will  often  skid  the  wheels. 

If  the  low  engages  in  a  jerky  manner,  if  the  car  climbs  hills 
badly,  or  if  the  motor  seems  to-  run  faster  than  it  should  when 
in  low  gear,  it  is  likely  that  low  speed  brake  band  needs 
relining.  When  engaging  the  low  speed,  the  pedal  should  be 
brought  down  smoothly  and  firmly  and  as  soon  as  gear  is 
engaged  the  pedal  should  "be  held  so  that  there  is  no  slipping 
and  wear  on  the  drum  or  band.  As  the  reverse  is  seldom 
used  it  can  be  us^d  for  a  brake  to  distribute  the  wear,  but  it 
should  not  be  used  to  make  a  full  stop  as  it  is  likely  to  stall 
the  motor.  As  far  as  possible,  coast  to  a  stop. 

Breaking  in  a  Ford  Car. 

In  starting  a  Ford  for  the  first  time,  the  chief  point  to 
bear  in  mind  is  that  excessive  speed,  if  long  continued,  will 
be  certain  to  lead  to  trouble.  If  it  is  driven  at  an  average 


136  MOTORS  AND  MECHANISM 

speed  of  20  miles  per  hour  it  will  last  for  years,  but  if  driven 
at  30  miles  its  life  may  be  counted  in  months,  especially  when 
a  good  share  of  the  work  is  performed  on  country  roads. 
During  the  first  500  miles  of  its  life  one  should  be  particularly 
careful  to  avoid  over-driving,  although  the  temptation  to  try 
out  a  new  car  is  almost  irresistable.  The  new  parts  are  as  yet 
unaccustomed  to  one  another,  the  bearings  are  stiff  and  likely 
to  overheat  and  the  piston  rings  are  not  yet  thoroughly 
adapted  to  the  cylinder  bore.  It  takes  a  little  time  for  the 
parts  to  "sweeten"  and  for  the  shafts  to  burnish  the  bearing 
surfaces. 

When  started  off  on  hard  work  from  the  very  beginning 
the  tiny  rough  spots  cause  a  great  friction  which  appears  in 
the  form  of  heat.  The  heat  thus  produced  causes  the  parts  to 
expand,  thus  still  further  increasing  the  tightness  of  the 
bearings.  In  the  end  this  will  either  result  in  scoring  the  sur- 
faces or  seizing  in  extreme  cases.  As  the  coefficient  of  friction 
in  an  old  bearing  is  much  lower  than  in  a  new,  the  heat  is 
developed  more  slowly  and  the  scoring  is  less  likely.  Again, 
in  the  new,  tight  bearings,  the  oil  does  not  flow  over  the 
surfaces  as  readily  as  in  an  old  bearing. 

It  is  not  advisable  to  drive  faster  than  20  miles  per  hour 
during  the  first  500  miles,  and  the  average  speed  should  be 
preferably  less  than  this,  say  15  to  18  miles. 

Ford  Oiling  Troubles. 

Usually  the  front  cylinder  of  a  Ford  motor  gets  too  much 
oil,  causing  the  plug  in  that  cylinder  to  soot  rapidly  and  cause 
misfiring.  The  "remedy  is  to  cut  down  the  oil  until  it  is  not 
high  enough  in  the  flywheel  reservoir  to  run  out  of  the  upper 
test  cock  but  just  high  enough  to  run  out  of  the  lower.  Avoid 
using  too  little  oil  in  your  endeavor  to  correct  this  fault ;  the 
exact  amount  is  best  taught  by  daily  observation.  The  oil 
supply  pipe  runs  forward  through  the  crank  case  delivering 
the  oil  near  the  front  cylinder  so  that  the  front  is  the  first  to 
suffer  in  case  of  an  excess  of  oil  in  the  reservoir. 

Sooting  of  the  plugs  due  to  an  excess  of  oil  may  also  be 


MOTORS  AND  MECHANISM  137 

due  to  the  enclosing  of  the  valve  stems  by  the  side  plate.  Any 
wear  in  the  valve  stem  holes  will  cause  oil  to  be  drawn  up  and 
into  the  cylinders  and  on  the  plugs.  Removal  of  the  cover 
plate  will  stop  this  annoyance. 

Overheating. 

Obstructions  in  the  cooling  system  such  as  deposits  of  lime 
from  hard  water,  a  shred  of  rubber  broken  free  from  the  hose, 
or  air-bound  connections,  will  cause  overheating.  A  retarded 
spark  with  the  throttle  fully  opened  or  a  defective  timer 
spring  will  also  cause  the  trouble.  Restricted  lubrication  or 
tight  bearings  are  often  accountable.  An  excessively  rich 
mixture  delays  combustion  and  transmits  a  great  amount  of 
heat  to  the  jacket  water. 

The  radiator  should  be  tested  by  placing  the  hand  at  various 
points  to  see  if  the  heat  is  uniformly  distributed.  If  it  is  cool 
in  spots  it  is  evident  that  the  radiator  is  clogged  at  some  point. 
Examine  the  hose  and  connections  carefully  for  deposits  or 
for  loosened  layers  of  rubber.  When  driving  at  a  iair  speed 
keep  the  spark  well  advanced,  nearly  to  the  knocking  point ; 
never  let  the  spark  be  retarded  with  the  throttle  opened  to 
any  extent. 

Leakage  past  the  piston  rings  due  to  bad  rings  or  to  an 
uneven,  wavy  cylinder  bore  allows  the  hot,  burning  gas  to 
sweep  the  oil  from  the  cylinder  walls,  increases  the  friction 
and  hence  the  heat.  Any  considerable  amount  of  the  gas  pass- 
ing the  piston  rings  also  increases  the  radiating  surface  and 
the  heat  transmitted  to  the  jacket  water. 

Leakage  of  water  past  the  cylinder  head  gasket  produces 
steam  in  the  cylinder  which  in  turn  destroys  the  oil  film  be- 
tween the  piston  and  the  cylinder  walls.  When  the  oil  film 
is  once  destroyed,  the  increased  friction  causes  heat  and 
trouble  with  the  cooling  system. 

In  some  cases,  overheating  has  been  caused  by  covering  the 
radiating  face  of  the  radiator  with  large  license  tags  or  signs. 
Fully  closing  a  radiator  cover,  used  for  protection  in  winter, 


138  MOTORS  AND  MECHANISM 

will  also  cause  the  same  trouble.  See  that  the  license  numbers 
do  not  keep  the  air  from  freely  entering  the  radiator,  especially 
in  hot  weather. 

A  broken  or  loose  fan  belt  will  cause  the  motor  to  overheat, 
especially  when  standing  idle.  Sediment  or  gummy  deposits 
from  anti-freezing  solutions  clog  up  the  cooling  system.  See 
that  the  cylinder  head  gaskets  do  not  obstruct  the  flow  of 
water  from  the  cylinder  casting  to  the  cylinder  head. 

Missing  and  Knocking. 

» 

Missing  and  jerking  of  a  Ford  car  may  be  due  to  a  variety 
of  causes,  a  poor  mixture,  irregular  ignition,  or  trouble  in  the 
motor  proper.  Sooted  plugs,  especially  the  plug  in  the  front 
cylinder,  may  cause  the  missing  due  to  an  excess  of  oil  (see 
Oiling  Troubles).  A  wabbling  or  dirty  timer  will  cause  the 
same  trouble,  as  will  sticking  vibrator  points  on  the  spark  coil. 
Broken  insulation  on  the  wires,  broken  spark  plug  porcelains, 
weak  batteries  or  magneto  trouble,  are  also  causes  of  misfir- 
ing. 

On  old  cars,  misfiring  is  frequently  caused  by  worn  valve 
stem  guides  admitting  air  into  the  manifold  and  ports.  This 
air  of  course  dilutes  the  mixture  and  causes  the  greatest  differ- 
ence when  the  throttle  is  well  closed  and  when  the  suction  is 
the  greatest.  The  effect  due  to  air  leaks  is  the  least  at  high 
speeds,  as  the  suction  is  less  and  the  requirements  for  a  lean 
mixture  are  greater  than  at  low  speed.  A  motor  in  this  con- 
dition does  not  idle  well.  Misfiring  will  usually  produce 
knocking. 

Another  source  of  knock  in  a  Ford  is  that  of  the  cylinder 
head,  which  by  projecting  into  the  bore  intermittently  comes 
into  contact  with  the  piston.  The  knock  produced  by  a  loose 
crankshaft  is  more  pronounced  on  a  heavy  pull  or  when  run- 
ning at  about  15  miles  per  hour.  At  higher  speeds  the  blows 
are  so  rapid  that  the  noise  disappears.  Knocks  due  to  loose 
connecting  rods  and  piston  pins  are  more  noticeable  when  the 


MOTORS  AND  MECHANISM  139 

load  is  suddenly  released  or  when  idling.  The  knock  due  to 
the  piston  striking  the  cylinder  head  is  regular  and  is  prac- 
tically of  the  same  intensity  at  all  times. 

The  cylinder  head  gasket  should  be  installed  with  the 
pistons  of  cylinder  1  and  4  projecting.  Now  lay  gasket  brass 
side  up  so  that  it  clears  both  pistons  by  a  sufficient  distance 
to  prevent  it  from  touching  when  squeezed  out  by  the  pressure 
of  the  bolts.  Now  lay  the  cylinder  head  in  position,  making 
sure  that  the  bolt  holes  are  clear  of  any  accumulation.  Insert 
all  bolts  about  half-way  and  move  the  head  so  that  it  will 
clear  all  pistons  when  the  engine  is  turned  over  by  hand. 
Any  dirt  in  the  bolt  holes  will  cause  the  head  to  shift  so  that 
it  will  be  struck  at  the  upper  end  of  the  piston  stroke. 

Oftentimes  it  will  be  found  that  the  knock  is  not  in  the 
motor  at  all,  but  is  due  to  a  broken  tooth  in  the  driving  gear, 
or  to  play  in  the  universal.  Both  these  troubles  often  sound  as 
if  they  were  located  in  the  motor. 

Care  of  Ford  Running  Gear. 

Once  every  month,  the  front  and  rear  axles,  bushings  in 
spring  hangers,  steering  knuckles,  and  hub  bearings,  should 
be  inspected  and  lubricated.  See  that  the  nuts  and  cotter 
pins  are  all  in  place  and  that  the  spring  clips  which  fasten  the 
springs  to  the  frame  are  in  proper  condition.  To  remove  the 
front  axle  jack  up  front  end  of  car,  disconnect  steering  gear, 
radius  rods  at  ball  joints,  and  the  two  cotter-pinned  bolts  from 
shackle  on  each  side,  thus  releasing  front  spring. 

If  the  axle  or  spindle  should  be  bent  care  must  be  taken  in 
straightening,  as  the  work  must  be  done  cold  to  prevent  draw- 
ing the  temper.  It  is  better  to  return  them  to  the  factory  for 
this  repair.  It  is  essential  that  the  wheels  line  up  since  exces- 
sive tire  wear  will  result  from  poor  alignment.  The  wheels 
should  be  jacked  up  and  tested  periodically  for  looseness 
and  side  play.  If  a  sharp  click  occurs  now  and  then  in  spin- 
ning the  wheel  and  the  wheel  is  momentarily  checked,  it  is 
likely  that  there  is  a  split  or  cracked  ball.  This  should  be 


140  MOTORS  AND  MECHANISM 

removed,  for  in  time  it  will  destroy  the  entire  bearing.  A 
wheel  in  perfect  adjustment,  after  spinning,  should  come  to 
rest  with  the  tire  valve  directly  below  the  hub. 

Speeding  a  Ford. 

While  the  Ford  is  not  primarily  built  for  speed,  it  can  be 
"doped  up"  so  that  the  results  obtained  will  be  rather  sur- 
prising to  those  who  have  only  driven  stock  models.  The 
increased  speed  it  should  be  remembered  greatly  shortens  the 
life  of  the  car,  and  the  changes  suggested  herein  should  only 
be  attempted  when  a  good  money  prize  or  other  considera- 
tion is  offered  that  will  offset  the  expense  of  the  change  and 
the  depreciation  of  the  car. 

The  first  thing  to  attend  to  is  the  reduction  of  weight  and 
wind  resistance,  this  being  accomplished  by  removing  unnec- 
essary parts,  such  as  the  body,  top,  windshield,  fenders  and 
running  boards.  A  low  racing  body  with  bucket  seats  can 
then  be  obtained  from  any  dealer  in  Ford  supplies  and  fitted 
to  the  chassis.  These  can  be  had  at  so  low  a  price  that  it 
does  not  pay  to  make  them.  The  steering  wheel  can  now  be 
lowered  to  fit  the  new  driving  seat.  At  this  point  we  wish 
to  remark  that  unless  the  future  racing  man  is  a  good  me- 
chanic he  had  better  add  at  least  one  automobile  garage  man 
to  his  payroll  for  some  of  these  alterations  require  considerable 
experience  and  skill.  Changing  the  steering  column  requires 
tools  and  a  knowledge  of  automobile  detail. 

More  power  is  required  and  therefore  the  compression 
must  be  increased.  This  is  generally  accomplished  by  plan- 
ing down  the  top  of  the  cylinder  head  by  about  one-eighth  inch 
so  that  the  volume  of  the  combustion  chamber  is  diminished 
and  the  compression  raised  to  approximately  60  pounds  per 
square  inch.  For  this  operation  the  motor  must  be  removed 
from  the  chassis.  The  valve  timing  must  be  changed  to  meet 
the  increased  motor  speed,  and  the  lift  of  the  cams  increased 
to  allow  the  charge  to  enter  more  freely  and  the  exhaust  to 
leave  without  back  pressure, 


MOTORS  AND  MECHANISM  141 

In  regard  to  the  timing,  it  is  practically  impossible  to  give 
any  definite  instructions  except  that  exhaust  and  inlet  valves 
must  both  open  earlier,  and  the  inlet  must 'stay  open  longer. 
The  exact  amounts  by  which  these  alterations  are  made  are 
usually  a  matter  of  individual  experiment  since  it  is  seldom 
that  two  motors  will  perform  in  exactly  the  same  way.  The 
old  camshaft  must  be  removed  and  a  new  one  installed,  prefer- 
ably with  separate  cams.  By  using  separate  cams  keyed  on 
the  shaft  it  is  easier  to  make  changes  in  the  timing  than  when 
integral  cams  are  used;  at  least  they  are  preferable  during 
the  experimental  period.  After  the  best  arrangement  has 
been  found,  a  new  integral  camshaft  can  be  made  to  cor- 
respond with  the  experimental  camshaft.  To  increase  the 
lift  of  the  valves,  the  peak  height  of  the  cams  must  be  increased 
by  approximately  one-eighth  inch. 

To  insure  prompt  closing  the  weight  of  the  valves  should 
be  decreased  as  far  as  commensurate  with  safety,  and  the 
tension  of  the  valve  springs  should  be  increased.  The 
muffler  and  old  exhaust  pipe  must  be  removed  and  replaced 
by  short  pipe  nipples  that  just  reach  beyond  the  hood,  one 
nipple  for  each  cylinder.  If  the  mpples  are  of  "L"  form  with 
the  open  ends  pointed  toward  the  back  of  the  car,  the  scav- 
enging effect  on  the  exhaust  gases  will  be  increased  and  the 
suction  created  will  be  an  aid  to  the  entering  mixture  under 
certain  conditions  of  valve  timing. 

As  the  motor  will  run  much  faster  under  racing  conditions, 
it  is  advisable  that  the  igni-tion  be  changed,  or  at  least  the 
arrangement  of  the  commutator.  The  short  segments  and  the 
increased  electrical  resistance  due  to  the  higher  magneto 
frequency  will  cut  down  the  primary  current  at  the  high  speed' 
that  we  expect  to  attain.  Either  a  high  tension  magneto,  or 
a  battery  system  similar  to  the  Atwater-Kent  will  act  well 
at  high  speed.  In  any  event,  a  master  vibrator  should  be  used 
if^the  old  coils  are  to  be  used. 

Owing  to  the  increased  compression  and  higher  speed  it 
will  be  necessary  to  carefully  lap  in  the  rings  and  weigh  all 
of  the  pistons.  In  some  cases  it  is  desirable  to  use  the  new 


142  MOTORS  AND  MECHANISM 

form  of  high  compression  rings.  If  all  of  the  pistons  are  not 
of  the  same  weight  they  must  be  cut  down  or  new  ones  ob- 
tained in  order  to  reduce  vibration  at  high  speed.  The  new 
aluminum  alloy  pistons  are  just  the  thing  for  this  purpose 
for  they  reduce  the  vibration  and  the  bearing  pressures  due  to 
inertia.  Balance  the  connecting  rods  in  the  same  way. 

Next,  we  must  pay  attention  to  the  lubrication  system  and 
increase  the  amount  of  oil  fed  to  the  bearings  by  increasing 
the  size  of  the  oil  pipe  inside  of  the  crank  case.  Holes  are 
cut  in  this  pipe  opposite  to  each  connecting  rod,  and  a  hand 
oil  pump  is  added  for  forcing  oil  into  the  crank  case.  The 
main  and  connecting  rod  bearings  are  grooved  for  a  better 
distribution  of  oil  over  the  bearing  surfaces. 

It  is  necessary  to  change  the  rear  axle  gearing  to  obtain  a 
higher  gear  ratio  between  the  motor  and  road  wheels.  Racing 
gears  for  Ford  cars  can  be  obtained  from  specialty  dealers 
which  are  interchangeable  with  the  stock  gears,  making  it  an 
easy  matter  to  install  them.  Oversize  tires,  31x4  inches,  are 
more  durable  under  racing  conditions  than  the  stock  30x31/2 
used  on  the  rear  wheels. 

To  make  the  car  hold  the  road  better,  shock  absorbers  of  the 
usual  Ford  type  should  be  fitted.  Wire  wheels  in  place  of 
the  stock  wheels  are  lighter,  stronger  and  easier  on  the  tires. 
A  letter  recently  written  to  "Motor  Age"  states  that  the  inlet 
and  exhaust  manifolds  were  increased  to  1%  inches  in  bore 
and  that  a  l^-inch  Schebler  carbureter  was  used.  The  cyl- 
inders were  bored  oversize,  and  a  gear  ratio  of  3  to  1  was 
used.  In  answer  to  this  letter  the  editor  of  the  Reader's  Clear- 
ing House  proposes  the  following  timing  for  a  racing  Ford : 

Inlet  opens  5  degrees  after  upper  dead  center. 

Inlet  closes  50  degrees  past  lower  dead  center. 

Exhaust  opens  42  degrees  before  lower  dead  center. 

Exhaust  closes  5  degrees  after  upper  dead  center. 

This  he  claims  is  only  a  basis  on  which  to  begin  experi- 
mental work,  as  the  exact  value  will  differ  in  individual  cars. 
The  car  described  by  the  contributor  gave  69  miles  per  hour  on 
a  one-half  mile  speedway. 


MOTORS  AND  MECHANISM  143 

Ford  Car  Speed  Changing. 

In  coming  down  from  high  to  slow  speed  on  a  hill  do  not  let 
the  engine  race.  Close  the  throttle  just  before  you  push  the 
pedal  forward,  so  that  when  you  reach  free-engine  point  the 
engine  will  be  only  just  comfortably  turning  over.  Engage 
slow  speed,  and  then  gradually  open  the  throttle  as  far  as  is 
necessary  to  carry  you  comfortably  on.  Do  not  try  to  rush  a 
hill  on  slow  speed.  If  you  race  the  engine  between  high  and 
slow  speed,  you  will  engage  slow  speed  with  a  jerk  that  will 
mean  discomfort  for  all  in  the  car — to  say  nothing  of  the  engine 
itself. 

In  picking  up  high  speed  you  let  the  pedal  come  back  from 
slow,  close  the  throttle  a  little,  and  the  clutch  will  then  take 
hold  "sweetly."  You  ought  not  to  jump  forward  with  a  bound. 
If  there  is  the  slightest  disinclination  on  the  part  of  the  clutch 
to  take  up  the  load,  slip  it,  by  pressing  the  clutch  pedal  slightly 
forward  again,  going  right  forward  into  low  speed  once  more, 
if  both  car  and  engine  have  lost  most  of  their  momentum.  It 
ought  to  shock  your  mechanical  sense  to  feel  the  engine  labor- 
ing in  the  effort  to  pick  up  the  clutch.  Another  point — not  so 
important.  Retard  the  spark  slightly  when  picking  up  the  high 
speed,  advancing  it  as  you  get  way  on, 


144  MOTORS  AND  MECHANISM 

x 

CHAPTER  IX 
IGNITION— MAGNETOS— SELF-STARTERS 

In  Fig.  1  is  shown  a  perspective  view  of  a  typical  true  high- 
tension  type  magneto,  the  magnets  and  pole  pieces  being 
omitted  for  the  sake  of  simplifying  the  drawing.  The  arma- 
ture lies  between  the  pole  pieces  and  magnets  in  the  same 
manner  as  in  the  elementary  magneto  previously  described. 
At  the  right  of  the  perspective  is  a  section  through  the  arma- 
ture showing  the  actual  arrangements  of  the  two  windings 
on  the  armature,  the  winding  in  the  perspective  being  simply 
diagrammatic.  The  shuttle  armature  of  "H"  form  is  indicated 
by  H  in  both  views. 

This  armature  is  connected  to  the  shafts  D  and  N  by  two 
brass  end  plates  similar  to  F.  The  body  of  the  armature  in 
general  is  built  up  of  a  laminated  sheet  steel  to  prevent  the 
generation  of  useless  eddy  currents  and  to  increase  the  strength 
of  the  magnetic  flux  through  the  armature  winding.  The 
primary  winding  is  grounded  to  the  armature  core  at  the 
point  Y,  and  is  then  given  several  turns  around  the  iron  core 
K,  the  outer  end  of  the  winding  being  connected  to  the  con- 
nection bolt  2B  at  the  point  M.  It  should  be  remembered 
that  the  primary  winding  consists  of  a  few  turns  of  heavy 
wire. 

From  the  point  M,  the  secondary  winding  consisting  of 
thousands  of  turns  of  very  fine  wire  is  started.  The  inner 
end  of  the  secondary  being  connected  to  M  makes  the  sec- 
ondary simply  a -continuation  of  the  primary  winding.  This 
is  not  shown  in  the  perspective  as  it  would  greatly  compli- 
cate the  drawing,  but  the  true  arrangement  can  be  easily  seen 
from  the  section  at  the  right  in  which  J  is  the  primary  and 
L  is  the  secondary,  an  insulating  strip  G  separating  the  two 
parts  of  the  circuit.  The. entire  series  of  winding  is  insulated 


MOTORS  AND  MECHANISM 


145 


from  the  core  by  the  insulation  indicated  by  the  heavy  black 

lines.    A  band  I  binds  the  wire  against  the  centrifugal  force 

that  tends  to  burst  the  winding  when  the  armature  is  rotating. 

Primary  current  is  carried  to  the  circuit  breaker  jaw  2A 


FIG.  1.— TYPICAL  TRUE  HIGH  TENSION  TYPE  MAGNETO  SHOWING 
CONSTRUCTION  AND  CIRCUIT  IN  DIAGRAMMATIC  FORM. 


and  the  switch  2D,  through  the  insulated  connection  bolt  2B, 
which  is  insulated  from  the  shaft  N  by  the  black  insulation 
shown.  The  outer  end  of  the  high-tension  winding  is  car- 
ried to  the  high-tension  collector  ring  E  by  means  of  the  insu- 
lated pin  2E.  A  brush  at  2B  carries  primary  current  to  the 


146  MOTORS  AND  MECHANISM 

grounding  switch  2D,  which  when  closed  grounds  the  pri- 
mary and  stops  the  generation  of  high-tension  current.  This 
switch  is  generally  placed  on  the  dash  of  the  automobile. 

A  primary  circuit  breaker  jaw  2A,  which  is  connected  to 
the  primary  winding,  and  is  insulated  from  the  shaft,  revolves 
with  the  shaft  and  makes  intermittent  contact  with  the  jaw 
X  at  the  point  Z.  The  jaw  X  is  grounded  to  the  shaft  and 
revolves  with  it  so  that  the  two  contact  points  are  always 
opposite  to  one  another.  Every  time  that  contact  is  made 
between  the  two  jaws  at  Z,  the  primary  circuit  is  completed 
through  the  ground.  The  opening  and  closing  of  the  jaws 
is  accomplished  by  means  of  a  stationary  cam  which  acts  on 
the  cam  roller  2C,  the  contact  between  the  cam  and  roller 
being  made  twice  per  revolution. 

When  the  contact  is  broken,  the  primary  circuit  is  opened, 
which  gives  a  heavy  current  impulse  to  the  secondary  wind- 
ing, this  impulse  resulting  in  a  spark  at  the  plugs.  The 
spark  therefore  occurs  at  the  instant  when  the  breaker  opens 
the  circuit.  The  cam  that  opens  the  jaws  is  usually  made  of 
fiber  board,  and  is  located  in  the  breaker  housing  that  covers 
the  mechanism.  In  some  types  of  magnetos  the  cam  revolves 
against  stationary  breaker  jaws,  but  this  is  merely  a  matter 
of  detail  and  in  no  way  affects  the  principle  of  operation. 
The  contact  points  Z  are  either  of  platinum-iridium  or  of 
metallic  tungsten. 

By  shifting  the  breaker  housing  to  the  right  or  left  by 
means  of  lever,  the  breaker  jaws  open  sooner  or  later  in  the 
revolution  of  the  armature,  causing  the  advance  or  retard 
of  the  spark.  This  is  similar  to  the  effect  produced  by  rock- 
ing the  housing  of  the  battery  timer. 

A  distributor  board  is  shown  in  the  perspective  which  con- 
tains the  metal  sectors  S-S2-S3-S4,  each  of  these  . sectors 
being  connected  to  the  wires  1-2-3-4,  which  lead  to  the  spark 
plugs  in  the  cylinders.  These  sectors  receive  high-tension 
current  from  the  brush  T  contained  in  the  revolving  distrib- 
uter arm  V,  each  sector  being  charged  in  turn  as  the  arm 


MOTORS  AND  MECHANISM  14? 

revolves.  The  distributer  board  is  of  course  built  of  some 
high  insulating  material  such  as  hard  rubber  or  Bakelite,  and 
is  shown  as  if  it  were  transparent  so  that  the  armature  parts 
may  be  clearly  seen.  A  spring  U  forces  the  brush  into  con- 
tact with  the  sectors  and  also  electrically  connects  the  brush 
with  the  high-tension  current  coming  through  the  connector 
shaft  V  and  the  second  high-tension  brush  holder  Q. 

High-tension  current  from  the  secondary  winding  passes 
from  the  connection  2E  to  the  collector  ring  E,  this  ring 
being  thoroughly  insulated  from  the  frame  by  the  hard  rub- 
ber bushing  D,  shown  in  solid  black.  The  high-tension  cur- 
rent is  taken  from  the  collector  ring  by  the  brush  C,  through 
the  insulating  support  B,  and  to  the  terminal  A.  From  A  the 
current  passes  through  the  bridge  P  to  the  distributer  arm 
U  through  the  brush  holder  Q  and  the  connector  V. 

The  current  passes  to  the  plugs  through  1-2-3-4,  and  the 
plugs  being  grounded,  the  current  returns  through  the 
grounded  frame  to  the  armature  coil  through  the  arms  X  and 
2A  at  the  moment  of  contact. 

The  distributer  arm  V  is  driven  through  a  gear  (not  shown) 
from  a  pinion  on  the  armature  shaft  N.  With  four-cylinder 
motors  the  distributer  travels  at  camshaft  speed  or  at  one- 
half  of  the  armature  speed,  since  the  armature  of  a  four- 
cylinder  motor  always  travels  at  crankshaft  speed. 

With  a  six-cylinder  motor,  the  armature  travels  at  one  and 
one-half  times  the  crankshaft  speed,  and  as  the  distributer 
still  travels  at  camshaft  speed,  the  gear  ratio  between  the 
armature  and  distributer  is  3  to  1.  Single-cylinder  and  two- 
cylinder  magnetos  have  no  distributer,  the  current  being  taken 
directly  from  the  collector  ring  E.  In  a  type  of  magneto 
recently  developed  for  small  four-cylinder  cycle  cars,  there 
is  no  distributer  in  the  ordinary  sense  of  the  word,  the  dis- 
tribution being  accomplished  by  two  split  collector  rings. 

The  following  table  will  give  the  armature  speeds  for  dif- 


148 


MOTORS  AND  MECHANISM 


ferent  numbers  of  cylinders.  It  should  be  remembered  that 
in  all  cases  the  distributer  runs  at  camshaft  speed,  and  that 
there  are  as  many  distributer  sectors  as  there  are  cylinders: 

(Four-Cycle  Type  Motors  Only) 


No.  Cylinders 

Distributer 
Gear  Ratio 

Armature   Speed 

Note 

One 

No.  Dist. 

Crankshaft  Speed 

Two 

No.  Dist. 

Crankshaft  Speed 

Three 

l^tol 

Y±  Crankshaft 

Speed 

s 

Four 

2  to  1 

Crankshaft  Speed 

*Five 

No.  Dist. 

5/4  times  Crank- 

Rotary Motor 

shaft  Speed 

Dist.  on  Motor 

Six 

atoi 

\Y2   times  Crank- 

shaft Speed 

*Seven 

No.  Dist. 

1^4   times   Crank- 

^Rotary Motor 

shaft  Speed 

Dist.  on  Motor 

Eight 

4  to'! 

2  times   Crank- 

shaft Speed 

Single  Magneto 

Eight 

2tol 

Crankshaft  Speed 

Two  Magnetos 

• 

(each  4  cyls.) 

*Nine 

No.  Dist. 

9/4  times   Crank- 

Rotary Motor 

shaft  Speed 

Dist.  on  Motor 

fTen 

"'       5  to  1 

2.l/2   times   Crank- 

shaft Speed 

Radial  Aero  Type 

Twelve 

6  to  I 

3  times   Crank- 

One Magneto  for 

shaft  Speed 

Twelve  Cyls. 

Twelve 

3  to  1 

\l/2   times   Crank- 

Two Magnetos 

shaft  Speed 

(each  for  6  cyls.) 

*  Denotes  the  arrangement  used  with  rotary  engines  in  which  no 
magneto  distributer  is  used,  the  plugs  of  the  rotating  cylinders  coming 
into  contact  with  a  stationary  brush  held  by  the  magneto.  The  mag- 
neto is  of  the  single-cylinder  type. 

t  Denotes  a  radial  arrangement  of  cylinders,  all  cylinders  being  sta- 
tionary. Seldom  used. 

Typical   Transformer  Type   Magneto. 

The  transformer  type  of  magneto  contains  a  circuit  breaker 
and  distributer  as  an  integral  part.  It  must  be  driven  posi- 
tively at  a  definite  speed,  the  exact  speed  in  relation  to  the 


MOTORS  AND  MECHANISM 


149 


crank  shaft  being  determined  by  the  number  of  cylinders  in 
the  motor,  or  the  cycle  of  the  motor.  A  single  primary  wind- 
ing Z  of  heavy  insulated  wire  is  placed  on  the  armature,  and 
the  inner  end  is  grounded  at  the  point  G-3,  thus  doing  away 
with  the  necessity  of  a  return  wire.  The  breaker  housing 


FIG.  2.— TYPICAL  TRANSFORMER  TYPE  MAGNETO. 


L  in  reality  comes  directly  in  front  of  the  armature,  but  in 
the  drawing  it  has  been  placed  below  so  that  the  a'rmature 
construction  can  be  more  readily  seen.  The  pole  shoes  P  of 
the  magnet  embrace  the  armature  in  the  usual  way,  A  lead 


150  MOTORS  AND  MECHANISM 

from  the  primary  winding  connects  with  a  connector  bolt  G, 
which  passes  through  the  hollow  shaft  U,  the  bolt  G  being 
insulated  from  the  shaft  by  the  insulating  tube.  A  copper 
brush  E  pressed  on  the  end  of  G  by  a  small  spring  in  the  rear, 
collects'  the  current  from  the  armature  and  delivers,  it  to  the 
circuit  wire  terminal  6,  from  which  it  flows  to  the  coil  ter- 
minal T-3.  From  the  terminal"  T-3  the  current  passes  to  the 
switch  contact  I,1  across  the  switch  blade  N,  where  the  cur- 
rent splits,  part  going  through  the  coil  and  part  flowing  back 
to  the  circuit  breaker  through  2,1  terminal  T-2,  and  ends  at 
the  breaker  contact  A.  A  platinum-pointed,  contact  screw  M 
is  adjustable  in  the  insulated  holder  A.  It  should  be  noted 
that  the  brush  E  is  insulated  from  the  frame  by  the  rubber 
bushing  F. 

A  rocking  breaker  arm  B  swings  on  the  pivot  I,  to  which 
it  is  grounded  to  the  frame  of  the  magneto,  this  arm  being 
swung  back  and  forth  by  the  cam  H,  which  is  mounted  on 
the  armature  shaft  U.  The  cam,  rotating  periodically,  strikes 
the  cam  roller  K  fastened  in  the  arm,  opening  and  closing 
the  contacts  mounted  in  the  ends  of  A  and  B  at  the  point  B. 
When  these  contacts  are  closed  the  armature '  circuit  is 
grounded  through  1  to  12,  the  dotted  lines  representing  the 
grounded  circuit.  A  pair  of  auxiliary  contacts,  C  and  D, 
mounted  on  the  back  of  the  rocker  and  on  the  timer  housing, 
respectively,  are  for  the  purpose  of  breaking  the  battery  cur- 
rent in  the  coil. 

When  the  points  separate,  the  current  is  broken  in  the  pri- 
mary circuit  of  the  coil,  causing  a  high  tension  spark.  A 
small  helical  spring,  not  shown,  pulls  the  arm  B  and  the 
roller  K,  so  that  it  is  at  all  times  in  contact  with  the  cam  H. 
Since  there  are  two  maximum  current  impulses  per  revolu- 
tion of  the  armature,  the  cam  H  is  set  so  that  the  current  is 
broken  twice  per  revolution  at  the  time  when  the  armature 
is  generating  its  greatest  voltage  The  timer  housing  L  may 
be  rocked  back  and  forth  by  the  spark  lever  19,  by  which 
the  spark  may  be  advanced  or  retarded.  Rocking  the  hous- 
ing causes  the  came  H  to  come  into  contact,  earlier  or  later, 


MOTORS  AND  MECHANISM  151 

with  the  roller,  thus  causing  the  spark  to  occur  earlier  or 
later  in  the  revolution.  The  battery  breaker  C-D  is  grounded 
at  G-2. 

The  spark  coil,  condenser,  safety  spark  gap,  the  terminals 
T-l,  T-2,  T-3,  T-4,  T-5  and  the  dash  switch  are  placed  in 
a  wooden  box  that  is  usually  mounted  on  the  dashboard  of 
the  automobile.  The  battery  is  connected  with  the  box  by 
T-4  and  T-5,  usually  marked  "Bat."  on  the  instrument.  The 
terminal  T-l,  marked  "3"  on  the  instrument,  is  grounded  to 
the  frame  of  the  machine,  while  cables  from  T-2  and  T-3, 
marked  "2"  and  "A,"  respectively  on  the  instrument,  are  con- 
nected with  the  stationary  breaker  contact  and  with  the  arma- 
ture brush  E. 

Around  the  soft  iron  core  T-T1  are  wound  the  primary 
and  secondary  windings  as  shown.  In  the  case  of  this  par- 
ticular machine,  the  secondary  winding  consists  of  3900  ohms 
of  No.  34  wire,  while  the  resistance  of  the  primary  is  only 
0.08  ohms,  the  ratio  between  the  windings  being  nearly  40,000 
to  1.  The  usual  type  of  tin  foil  condenser  is  connected  across 
the  primary  winding  of  the  wires  9-10  and  8-11,  this  prevent- 
ing sparking  at  the  contact  points  A  and  B,  and  acting  so 
as  to  increase  the  volume  of  the  secondary  spark. 

A  safety-spark  gap  is  connected  across  the  high  tension 
terminals  at  16  and  17,  the  distance  between  the  discharge 
points  being  regulated  so  that  the  spark  will  jump  across 
these  points  when  the  voltage  becomes  excessive  at  high 
speeds  or  in  cases  when  the  secondary  leads  become  discon- 
nected from  the  plugs.  Limiting  the  voltage  in  this  way 
does  away  with  .the  danger  of  puncturing  the  insulation  of 
the  high  tension  windings.  Usually  this  gap  is  about  % 
inch  wide,  and  at  speeds  above  800  revolutions  per  minute, 
or  with  more  than  4  cells  there  is  almost  a  continuous  dis- 
charge when  the  plugs  are  disconnected. 

A  press  button  P  is  used  for  causing  a  spark  at  the  plug 
when  the  engine  is  at  rest,  or  for  starting  on  "compression," 
as  it  is  called.  With  a  warm  engine,  having  its  cylinders  full 
of  mixture,  it  is  very  often  possible  to  start  the  engine  in 


152  MOTORS  AND  MECHANISM 

this  way  without  cranking.  The  spark  occurs  when  the  con- 
tacts P  and  O  are  separated,  the  points  P  and  O  permitting 
battery  current  to  flow  for  an  instant  through  the  primary 
of  the  coil. 

The  dash  switch  is  mounted  on  tne  front  of  the  coil  box 
and  has  two  switch  positions,  "Bat."  and  "Mag."  When 
starting  the  switch  indicator  is  thrown  to  "Bat.,"  and  when 
the  engine  is  firing  regularly  the  switch  is  thrown  to  "Mag.," 
thus  cutting  the  magneto  in  and  the  battery  out  of  service. 
The  normal  running  should  always  be  done  on  the  magneto. 

In  the  sketch  the  switch  is  shown  on  the  magneto  position, 
in  which  the  blade  N  shorts  the  contacts  I1  and  21,  bringing 
the  armature  current  from  6  to  the  breaker  contact  A.  At 
the  same  time  the  interrupted  armature  current  is  led  from 
the  switch  7  to  the  primary  of  the  coil  at  8,  and  from  the 
other  end  of  the  coil  at  9  to  the  ground  at  terminal  T-l,  and 
thence  back  -to  the  armature,  completing  the  circuit. 

End  17  of  the  secondary  coil  is  grounded  at  G,  this  connec- 
tion usually  being  to  the  lead  9  T-l,  as  this  saves  one  lead 
from  the  box  to  the  frame.  The  other  end  of  the  high  ten- 
sion wire  16  leads  through  15  to  the  axis  18  of  the  high 
tension  distributer.  From  the  coil  box  there  are  the  follow- 
ing cables  to  connect : 

2  wires  from  box  to  battery  (low  tension). 

2  wires  from  box  to  magneto  (low  tension). 

1  wire  from  box  to  ground  (low  and  high  tension). 

1  wire  from  box  to  distributer  (high  tension). 

4  wires  from  distributer  to  plugs. 

The  distributer  board,  shown  in  cross-hatch  lines,  is  made 
of  insulating  material  such  as  hard  rubber  or  Bakelite.  In 
this  material  are  imbedded  four  metal  sectors,  S-l,  S-2,  S-3 
and  S-4  spaced  at  equal  distances  around  the  circle.  It  must 
be  understood  that  there  are  as  many  sectors  as  cylinders, 
the  present  example  being  for  a  four-cylinder  motor. 

High  tension  current  from  the  secondary  of  the  coil  is 
brought  into  the  shaft  of  the  rotating  distributer  arm  R 


MOTORS  AND  MECHANISM  153 

through  the  wire  18-15-16.  As  the  arm  rotates  it  comes  into 
contact  with  the  sectors  in  order  and  thus  connects  the  high 
tension  current  to  the  spark  plugs  1-2-3-4  when  contact  is 
made  with  the  segments  S-l,  S-2,  S-3  and  S-4,  respectively. 
The  distributer  thus  connects  with  the  plugs  in  the  proper 
firing  order,  while  the  circuit  breaker  determines  the  part  of 
the  revolution  or  the  time  at  which  the  spark  is  to  occur. 

The  distributer  arm  R  is  driven  by  a  gear  on  the  shaft  18 
that  meshes  with  a  pinion  on  the  armature  shaft  U,  the  gear 
ratio  always  being  such  that  the  distributer  arm  turns  at 
cam-shaft  speed.  The  gear  ratio  between  the  armature  and 
the  distributer  varies,  however,  with  the  number  of  cylinders 
used. 

The  relation  of  the  magneto  speed  to  the  speed  of  the  motor 
or  crank-shaft  speed  depends  on  the  number  of  cylinders,  a 
single,  double  and  four-cylinder  magneto  running  at  exactly 
crank-shaft  speed,  while  a  three-cylinder  runs  at  %  crank- 
shaft speed  and  a  six-cylinder  at  1%  crank-shaft.  An  eight- 
cylinder  will  run  at  twice  crank-shaft  speed.  It  must  be 
understood  that  these  speeds  apply  only  to  four-stroke  cycle 
motors  and  to  shuttle  type  armatures  which  give  two  sparks 
per  revolution. 

Two-stroke  cycle  motors  demand  twice  the  number  of 
sparks  per  revolution,  and  for  the  same  number  of  cylinders 
as  each  cylinder  in  this  case  fires  twice  as  often.  For  the 
speeds  of  any  other  number  of  cylinders  see  the  table  under 
"Typical  True  High  Tension  Magnetos."  This  will  also 
apply  to  the  transformer  type. 

A  type  of  transformer  magneto  that  w^s  designed  by  the 
author  is  shown  by  Fig.  3.  In  this  magneto  the  transformer 
coil  was  enclosed  in  a  metal  case  and  placed  in  the  opening 
between  the  magnets,  thus  making  the  magneto  and  coil 
one  compact  unit  and  avoiding  the  use  of  many  wires  and 
cables  that  are  in  evidence  when  the  coil  is  mounted  on  the 
dashboard.  In  the  diagram  the  coil,  armature,  condenser 
and  circuit  breaker  are  shown  approximately  in  their  correct 
relative  positions. 


154 


MOTORS  AND  MECHANISM 


A  shuttle  armature  P  is  used,  one  end  of  the  primary  wind- 
ing being  grounded  to  the  armature,  while  the  other  end  is 
connected  with  insulated  bolt  D  with  the  lead  K.  The  heavy 
line  indicates  the  insulation.  A  brush  B  held  in  an  insulat- 
ing brush-holder  A  presses  on  the  enlarged  head  C  of  the 
connector  bolt  D,  thus  leading  the  armature  current  to  the 


FIG.  3.— ANOTHER  TYPE  OF  TRANSFORMER  MAGNETO. 


external  circuit  from  11.  One  lead  10-11  carries  the  arma- 
ture current  to  the  primary  coil  10-7.  Instead  of  depending 
on  the  armature  ground  connecting  with  the  magneto  frame 
through  the  shaft  and  bearings,  a  separate  grounding  brush 
L,  held  in  the  metal  holder  M,  was  used,  this  brush  ground- 
ing the  winding  at  G-2.  This,  as  far  as  the  diagram  goes, 
was  electrically  the  same  as  if  the  -inner  end  of  the  winding 
was  connected  to  the  frame,  but,  mechanically,  was  much 
better,  as  it  did  not  have  to  depend  on  a  ground  through  the 


MOTORS  AND  MECHANISM  155 

varying  conditions  caused  by  grease  or  loose  bearings.  Nt 
is  the  shaft. 

At  7  the  end  of  the  primary  is  grounded  at  G  and  is  con- 
nected through  the  frame  at  18,  and  to  brush  at  17,  all  dotted 
lines  representing  the  grounded  circuit.  A  tinfoil  condenser 
9-8  was  connected  across  the  coil  as  shown  by  9-10  and  7-8. 
A  safety  gap  5-6  was  connected  across  the  secondary  wind- 
ing, the  lead  5-0  going  to  the  high  tension  distributer  arm  O. 
This  arm,  in  rotating,  made  successive  contact  with  the  sec- 
tors leading  to  the  spark  plugs  1-2-3-4. 

The  other  end  of  the  armature  circuit  lead  from  the  brush 
Bat.  11  to  the  interrupter  at  R  through  wire  12.  This  inter- 
rupter consisted  of  two  metal  blades  G  and  H,  spring  tem- 
pered, mounted  and  insulated  from  each  other  on  the  block 
19.  Two  platinum  contact  points  I  and  J  made  normal  con- 
tact with  one  another,  grounding  the  armature  current  through 
15  at  G-3,  and  from  here  along  the  frame  15-16  and  16-17 
back  to  the  other  end  of  the  armature  winding. 

SINGLE— DUAL— DUPLEX— TWO-POINT   SYSTEMS. 

Magneto  Wiring  and  Connections. 

When  used  as  an  independent  source  of  ignition,  the  wir- 
ing of  a  magneto  is  a  very  simple  proposition,  but  when  used 
in  connection  with  a  battery  auxiliary,  the  amateur  electri- 
cian often  becomes  confused  with  the  multiplicity  of  wires 
and  connections.  The  additional  circuits  due  to  a  self-starting 
and  lighting  system  by  no  means  tend  to  simplify  matters. 

In  general,  the  circuit  of  an  independent  magneto  depends 
upon  the  type  of  magneto,  i.  e.,  whether  it  is  of  the  true  high 
tension  type  or  whether  used  in  connection  with  an  external 
spark  coil,  since  in  the  latter  type  there  are  several  primary 
wires  leading  from  the  magneto  to  the  coil  on  the  dash.  When 
this  system  is  "double/'  that  is  when  two  plugs  are  used  per 
cylinder,  the  high  tension  circuit  is  different  than  with  the 
single  system.  To  simplify  matters,  we  will  confine  our  at- 


156  MOTORS  AND  MECHANISM 

tention  at  present  to  the  combinations  commonly  used  with 
the  true  high  tension  type,  or  the  type  in  which  the  mag- 
neto windings  generate  the  high  tension  current  without  the 
use,  of  external  coils. 

Independent  Magneto — When  a  magneto  is  used  without 
batteries,  as  in  diagram  No.  1,  there  is  a  high  tension  lead 
from  each  plug  P  in  the  cylinders  to  a  corresponding  con- 
nection post  on  the  distributer  D.  A  primary  or  low  tension 
wire  leads  from  the  circuit  breaker  C  to  the  switch  S  located 
on  the  dash.  The  remaining  terminal  of  this  switch  is 
"grounded"  or  connected  to  the  frame  of  the  car  or  engine. 
With  some  late  types  of  magnetos  there  is  no  switch  S,  this 
short  circuiting  switch  being  embodied  in  the  circuit  breaker 
casing,  so  that  the  magneto  is  cut  out  by  moving  the  spark 
lever  on  the  wheel  to  "full  retard."  When  installing  the 
magneto  care  should  be  taken  to  have  the  magneto  base  in 
full  metallic  contact  with  the  frame  of  the  motor,  so  that  the 
magneto  will  also  be  effectively  grounded  for  the  return  of 
the  current.  The  advance  and  retard  of  the  circuit  breaker  is 
shown  by  A. 

Dual  System — In  the  dual  system  both  a  battery  and  mag- 
neto are  used,  the  former  being  used  in  starting  and  as  an 
auxiliary  against  the  failure  of  the  magneto.  With  the  dual 
system  a  single  set  of  plugs  is  used  for  both  the  magneto  and 
battery,  and  the  magneto  distributer  distributes  the  high 
tension  current  for  both.  The  usual  connections  are  shown 
by  Fig.  3,  in  which  CS  is  the  battery  spark  coil  and  switch 
mounted  on  the  dashboard,  B  is  the  battery,  M  is  the  mag- 
neto with  the  circuit  breaker  C  and  the  distributer  D.  And 
as  in  the  first  case,  P  are  the  plugs  in  the  cylinders. 

As  will  be  seen  from  the  diagram,  one  pole  of  the  battery 
is  grounded  to  the  frame,  as  is  also  one  terminal  of  the  coil. 

Duplex  System — In  the  duplex  system  both  the  magneto 
and  battery  are  used,  and  in  some  cases  an  independent  vibra- 
tor is  introduced  into  the  starting  system.  Instead  of  having 


MOTORS  AND  MECHANISM 


157 


/V6-.  A/a  4  - 


FIGS.  MA-2-3-4-5.— SHOWING  DIFFERENT  HIGH  TENSION  MAGNETO 
WIRING  SYSTEMS. 


i58  MOTORS  AND  MECHANISM 

a  separate  coil  for  the  battery,  as  in  the  dual  system,  the  pri- 
mary and  secondary  coils  on  the  magneto  armature  are  used 
to  produce  the  spark  when  the  battery  is  u$ed  In  this  type, 
the  circuit  breaker  and  distributer  of  the  magneto  are  used 
in  common  by  the  battery  and  magneto.  In  starting,  the 
switch  is  thrown  so  that  the  battery  current  passes  through 
the  primary  winding  of  the  magneto  armature,  the  interrupt- 
ing and  timing  being  performed  by  the  circuit  breaker,  each 
interruption  causing  a  spark  at  the  plugs.  The  high  tension 
current  from  the  secondary  winding  of  the  armature  is  led 
to  the  distributer  as  in  the  case  when  the  magneto  is  working 
alone. 

When  running  normally  on  the  magneto  alone,  the  bat- 
tery is  cut  out  of  circuit.  To  increase  the  spark  at  starting, 
the  Bosch  duplex  magneto  has  a  vibrator  in  series  with  the 
armature  (see  Fig.  2),  which  is  cut  out  in  normal  running. 
In  Fig.  2,  VC  is  the  combined  vibrator  and  dash  switch. 

Two-Plug  Independent  System — To  insure  complete  inde- 
pendence of  the  battery  and  magneto  systems,  the  circuits 
are  made  entirely  separate  from  one  another,  as  shown  by 
Fig.  4,  there  being  two  separate  sets  of  plugs  P  and  P,1  the 
first  for  the  battery  spark  and  the  second  for  the  magneto. 
Unlike  the  previous  systems,  there  is  a  distributer  BD  and 
circuit  breaker  for  the  battery  system,  and  a  circuit  breaker 
C  and  distributer  D  for  the  magneto  M.  The  battery  coil 
CS  carries  a  switch  which  opens  and  closes  either  independ- 
ent circuit.  The  battery  B  is  grounded  on  one  side. 

This  arrangement  makes  the  secondary  wiring  very  com- 
plicated and  difficult  to  arrange  properly  on  the  motor,  since 
there  are  twice  as  many  high  tension  leads  to  take  care  of. 
Since  the  plugs  are  the  most  common  source  of  trouble,  the 
complication  due  to  wiring  and  the  installation  of  a  separate 
distributer  do  not  make  this  system  advisable  in  ordinary 
cases.  The  comparatively  unused  battery  plugs  are  generally 
-foul  when  called  upon  in  an  emergency,  and  therefore  the 
system  is  little  more,  if  any,  reliable  than  the  dual  system 


MOTORS  AND  MECHANISM  159 

unless  one  wishes  to  assume  the  trouble  of  caring  for  twice 
the  necessary  number  of  plugs. 

Two-Point  System — To  increase  the  output  of  a  motor, 
especially  on  racing  cars,  it  has  been  common  practice  to 
have  two  sparks  occur  simultaneously  in  the  same  cylinder 
at  rather  widely  separated  points  in  the  com'bustion  chamber. 
Whether  this  amounts  to  any  material  increase  is  rather 
doubtful.  A  recent  test  run  showed  that  the  increase  was 
only  in  the  nature  of  5  per  cent,  an  amount  that  in  an  ordinary 
pleasure  car  would  hardly  justify  the  additional  complication 
and  expenses. 

By  installing  two  points  of  ignition  it  was  thought  that 
the  distance  through  which  the  flame  had  to  travel  would  be 
reduced,  since  there  were  two  points  from  which  the  flame 
would  spread.  An  increase  in  the  rate  of  combustion  ob- 
tained in  this  way  would  naturally  decrease  the  loss  of  heat 
to  the  jacket  water,  and  therefore  increase  the  power.  This 
effect,  of  course,  would  be  more  pronounced  in  the  case  of  a 
T-head  motor  where  the  distance  across  the  combustion 
chamber  is  at  a  maximum.  In  the  case  of  the  T-head  in  a 
certain  test  this  increase  amounted  to  10  per  cent  under  con- 
ditions very  favorable  to  the  system,  that  is,  the  cylinders 
were  very  large,  deeply  pocketed,  and  the  piston  velocity 
was  extremely  high.  With  the  automobile  in  ordinary  ser- 
vice the  advantages  are  questionable,  especially  with  L-head 
or  motors  having  overhead  valves. 

In  general  xthere  are  two  ways  of  producing  the  double 
spark  from  a  single  magneto.  (1)  By  providing  the  mag- 
neto with  a  double  distributer,  one  distributer  for  each  set  of 
plugs  and  arranged  so  that  each  distributer  causes  simulta- 
neous sparks  in  each  cylinder.  .(2)  By-  means  of  a  single  dis- 
tributer and  special  plugs,  one  plug  in  each  cylinder  being 
of  the  double  pole  variety  in  which  both  sparking  points  are 
insulated  from  one  another  and  from  the  metal  of  the  cylinder. 

The  first  method  is  shown  by  Fig.  5,  in  which  the  double 
distributers  D  and  D2  control  the  two  sets  of  spark  plugs  P 
and  P,2  respectively.  The  plugs  used  in  this  system  are  of 


160  MOTORS  AND  MECHANISM 

the  ordinary  type.  The  primary  connections  are  practically 
the  same  as  those  of  the  single  magneto,  and  the  system  can 
also  be  used  in  dual  with  the  battery. 

With  a  single  distributer,  the  high  tension  circuit  must  be 
arranged  so  that  the  current  passes  through  the  first  plug, 
across  the  points  to  the  second  plug  and  thence  to  ground 
or  to  the  cylinder  of  the  motor.  This  necessitates,  of  course, 
insulating  both  of  the  points  of  the  first  plug  from  the  cylin- 
der, for  if  either  of  the  points  make  contact  with  the  metal, 
no  current  will  flow  to  the  second  plug.  The  second  plug  is 
of  the  ordinary  variety. 

Electric  Starting  and  Lighting. 

General — When  using  electricity  as  a  medium  for  "crank- 
ing" the  gasoline  motor  it  is  possible  to  use  the  current  also 
for  ignition  and  lighting  as  well  as  for  the  electric  horn  and 
gear  shift.  The  possibility  of  operating  so  many  auxiliaries 
from  the  same  source  of  power  naturally  makes  the  electric 
self-starting  system  by  far  the  most  popular.  In  many  cases 
an  independent  magneto  is  used  and  sometimes  in  addition 
a  third  auxiliary,  the  dry  cell  system,  is  added  to  the  ignition 
.system  making  the  car  entirely  independent  of  any  one  sys- 
tem for  the  ignition  current. 

Disregarding  the  ignition  system  for  the  time  being,  the 
self-starting  and  lighting  system  is  composed  of  the  follow- 
ing principal  units : 

(1)  The  generator  for  supplying  the  current  for  the  crank- 
ing of  the  car  and  the  lighting  system. 

(2)  The  motor  for  spinning  the  motor.      (Sometimes  the 
generator  and  motor  functions  are  supplied  by  a  single  unit.) 

(3)  Storage  battery  for  storing  current  for  the  motor  and 
lights  as  well  as  for  the  horn  and  ignition. 

There  are  four  ways  in  which  a  single  unit  may  act  as  both 
generator  and  motor.  (1)  A  single  armature,  field  and  com- 
mutator may  give  or  receive  current  to  or  from  the  storage 
battery.  (2)  A  unit  with  a  single  field  and  armature  may  be 


MOTORS  AND  MECHANISM  161 

provided  with  two  commutators  and  two  independent  wind- 
ings on  the  armature,  one  winding  being  for  the  generator 
while  the  remaining  winding  and  commutator  is  for  motor 
service.  (3)  Two  independent  armatures,  fields  and  commu- 
tators may  be  contained  in  the  same  frame,  the  armatures 
being  mounted  on  the  same  shaft  in  tandem,  they  being  elec- 
trically independent  of  one  another  during  the  starting  and 
generating  periods.  (4)  Instead  of  being  in  tandem  the  fields 
and  armatures  may  be  mounted  in  the  same  casing  but  one 
above  the  other.  (Double  deck.) 

When  types  (1)  and  (2)  are  acting  as  generators  they  are 
generally  driven  by  the  engine  through  the  timing  gears. 
When  operating  as  motors  they  drive  the  engine  either 
through  a  gear  toothed  fly-wheel  or  by  a  silent  chain  to  the 
crank-shaft.  The  driving  pinion  is  so  arranged  that  it  can 
be  thrown  in  and  out  of  mesh  with  the  geared  fly-wheel  by 
the  starting  pedal,  the  gear  being  normally  out  of  mesh  when 
the  engine  is  running  under  its  own  power. 

Regulation  of  Generator  Current — The  faster  the  armature 
of  a  generator  rotates,  the  higher  will  be  the  voltage,  and  the 
greater  will  be  the  current  put  through  the  storage  battery-. 
With  a  continually  fluctuating  speed  due  to  the  variations  of 
the  engine  it  is  evident  that  some  device  must  be  provided 
that  will  limit  the  current  sent  through  the  storage  cells  and 
at  the  same  time  prevent  the  storage  battery  current  from 
surging  back  through  the  generator  when  the  generator  falls 
below  the  voltage  of  the  battery. 

In  general  there  are  four  ways  of  limiting  the  current. 
(1)  By  providing  the  generator  with  a  governor  so  that  it 
cannot  exceed  a  certain  speed.  (2)  By  placing  an  automati- 
cally controlled  resistance  in  the  generator  circuit  that  will 
keep  the  current  steady  at  any  ordinary  speed  of  the  gener- 
ator. (3)  By  providing  an  automatic  cut-out  switch  that  will 
open  the  circuit  when  the  current  exceeds  or  falls  below  cer- 
tain points.  (4)  By  inherent  regulation  of  a  specially  wound 
generator  in  which  the  windings  oppose  one  another  and 
diminish  the  output  as  the  speed  increases. 


162  MOTORS  AND  MECHANISM 

Double  Unit  System — There  are  several  systems  in  which 
the  generator  and  motor  are  entirely  independent  of  one  an- 
other and  are  mounted  in  different  parts  of  the  chassis.  The 
motor  is  series  wound  while  the  generator  is  compound 
wound,  the  difference  in  winding  being  due  to  the  fact  that 
a  series  winding  gives  greater  "torque"  or  pull  while  the 
compound  winding  tends  to  maintain  a  constant  current. 

The  Cut  Out — A  cut  out  is  an  automatic  switch  which 
opens  the  generator  circuit  when  the  voltage  of  the  gener- 
ator falls  belov^  that  of  the  battery  so  that  the  current  from 
the  battery  will  not  be  discharged  back  through  the  genera- 
tor. This  generally  consists  of  an  jron  core  on  which  a  dou- 
ble winding  is  placed.  One  winding  which  is  connected  across 
the  terminals  of  the  generator  consists  of  many  turns  of  fine 
wire,  while  the  other  coil  consists  of  a  few  turns  of  heavy 
wire  connected  in  series  with  the  circuit  leading  to  the  stor- 
age battery. 

When  the  generator  comes  up  to  voltage,  the  fine  wire 
coil  magnetizes  the  bar  so  that  the  armature  is  drawn  up 
causing  the  current  to  flow  into  the  battery  through  the 
switch.  The  main  current  now  flows  through  the  heavy,  coil 
reinforcing  the  magnetic  effect  of  the  first  coil. 

Should  the  generator  now  fall  in  speed  so  that  its  voltage 
is  less  than  that  of  the  battery,  the  current  will  be  reversed 
in  direction  through  the  second  coil  which  will  therefore 
oppose  the  first  coil,  demagnetize  the  iron  core  and  allow 
the  switch  to  be  opened  by  the  tension  of  a  spring  connected 
tb  the  armature. 

Generating  Speeds — All  other  conditions  being  constant, 
the  speed  of  a  dynamo  or  generator  determines  the  voltage, 
the  voltage  increasing  in  almost  direct  proportion  to  the  speed 
until  the  "saturation"  point  of  the  generator  is  reached.  To 
obtain  the  desired  voltage  it  is  therefore  necessary  to  have 
the  generator  run  at  a  particular  relation  to  the  normal  run- 
ning speed  of  the  motor.  Gearing  the  generator  at  a  high 
ratio  allows  the  current  to  be  developed  at  low  engine  speeds 


MOTORS  AND  MECHANISM 


163 


164 


MOTORS  AND  MECHANISM 


MOTORS  AND  MECHANISM  165 

Connecting  Motor  and  Generator  to  Engine. 

Connection  between  the  generator  and  the  motor  to  the 
engine  depends  to  a  great  extent  upon  the  arrangement  of 
the  engine  and  the  other  accessories,  the  three  principal  ar- 
rangements being  as  follows : 

(1)  Geared  connection  to  fly-wheel   (already  described). 

(2)  Chain  drive  to  crank  shaft,  or, 

(3)  Through    the    magneto    or    pump    shafts,    and    thence 
through  the  timing  gears  to  the  crank-shaft. 

In  addition  to  the  above  is  the  U.  S.  L.  system  in  which 
the  motor-generator  is  mounted  directly  on  the  crank-shaft 
in  place  of  the  usual  fly-wheel.  This  is  the  simplest  type  of 
all  since  it  dispenses  with  the  usual  gears,  bearings,  clutches 
and  shafts  of  the  other  systems,  and  reduces  the  weight  of 
the  machine  by  an  amount  approximately  equal  to  the  weight 
of  the  fly-wheel. 

When  the  drive  is  through  the  fly-wheel,  with  independent 
motor  (M)  and  generator  (G)  as  shown  in  Fig.  1,  the  motor 
end  is  cut  in  and  out  of  service  by  throwing  a  pinion  (A)  in 
or  out  of  mesh  with  the  teeth  cut  in  the  circumference  of  the 
fly-wheel  (F)  by  means  of  the  starting  foot  pedal  (P). 

A  switch  (S)  is  opened  or  closed  by  the  same  movement 
of  the  pedal  which  opens  or  closes  the  circuit  between  the 
storage  battery  (B)  and  the  motor.  Depressing  the  pedal 
throws  the  pinion  in  mesh  with  the  fly-wheel  and  closes  the 
switch  allowing  the  battery  current  to  flow  through  the  motor, 
thus  turning  the  crank-shaft  over  and.  starting  the  motor. 
The  second  set  of  reduction  gears  is  shown  at  (R).  A  resist- 
ance coil  (H)  is  generally  put  in  series  by  the  switch  which 
allows  the  motor  to  turn  over  very  slowly  until  the  gears 
are  in  mesh.  When  the  pinion  is  forced  clear  across  the  face, 
the  further  movement  of  the  switch  short-circuits  the  resist- 
ance, allowing  the  full  current  to  flow  and  the  motor  to  build 
up  its  full  speed. 

The  independent  generator  (G)  is  shown  in  driving  rela- 
tion to  the  crank-shaft  (C),  the  drive  being  through  the  silent 
chain  (D).  The  generator  in  this  system  is  always  con- 


1 66  MOTORS  AND  MECHANISM 

nected  to  the  crank-shaft  no  matter  whether  the  engine  is 
starting  or  running  normally.  A  cut-out  (E)  is  shown  in 
series  with  the  generator  circuit  (the  purpose  of  the  cut-out 
was  described  in  an  early  part  of  this  chapter).  The  dis- 
tributer (I)  is  shown  on  generator  feeding  the  spark  plugs 
(J),  the  coil  being  at  (K). 

In  Fig.  2  is  shown  the  motor-generator  arrangement  in 
which  the  functions  of  motoring  and  generating  are  per- 
formed by  a  single  unit  (L).  When  starting,  the  pedal  (P) 
meshes  the  pinion  (A)  with  the  fly-wheel  gear  teeth  (K)  as 
before  described,  the  switch  (S)  performing  the  same  way  as 
in  the  two  unit  system.  An  extension  of  the  armature  shaft 
is  driven  through  the  gear  train  (I)  when  the  unit  is  run- 
ning as  a  generator.  . 

Since  two  speeds  are  required  for  motoring  and  generat- 
ing it  is  evident  that  some,  form  of  slip  clutch  must  be  pro- 
vided as  at  (M)  so  that  the  armature  (G)  will  be  discon- 
nected from  the  gears  (I)  when  the  motor  is  starting  the 
engine  and  is  running  at  a  high  speed.  This  clutch  is  usually 
of  the  ratchet  type  which  will  allow  the  armature  shaft  to 
run  faster  than  or  to  run  past  the  gear  .(N). 

It  will  also  be  seen  that  with  this  type  there  are  two  inde- 
pendent commutators  (D)  and  (E)  for  the  two  windings 
on  the  armature  (G).  A  single  pair  of  poles  (H)-(H)  serve 
for  both  the  motor  and  generator  windings. 

Voltage  and  Battery  Arrangement — In  general  there  are 
three  voltage  arrangements  at  the  present  time,  a  straight 
system  where  lights,  motor  and  battery  operate  at  six  volts; 
a  straight  twelve  volt  system ;  and  a  mixed  system  in  which 
a  double  six  volt  battery  supply  current  at  twelve  volts  to 
the  motor  and  at  six  volts  for  the  lamps,  horn  and  ignition 
system. 

With  the  mixed  system,  the  twelve  volt  leads  are  con- 
nected from  the  end  terminals  of  the  battery,  while  the  six 
volt  circuit  is  obtained  by  a  third  wire  connected  to  the  mid- 
dle cell.  A  connection  made  between  this  third  wire  and  any 
of  the  others  gives  six  volts. 


MOTORS  AND  MECHANISM  167 

CHAPTER  X. 
DIFFERENTIAL  GEAR. 


Gear,  Differential — A  differential  gear,  sometimes  called  a 
"balance  gear,"  is  a  simple  device  which  is  misunderstood  by 
the  average  car  user,  partly  because  it  is  never  very  accessible, 
and  partly  because  it  is  very  difficult  to  describe  on  paper. 
A  British  writer  says :  "In  1827,  some  of  the  motor  'buses  which 
profitably  plied  for  hire  about  Cheltenham  and  in  London,  had 
each  of  their  wheels  fastened  by  a  pin  to  a  solid  rod  of  iron 
which  constituted  the  live  back  axle.  In  several  of  these 
'buses  the  axle  was  driven  by  a  chain,  but  none  of  them  had  a 
differential.  It  is  instructive  to  learn  what  happened. 

"When  they  wanted  to  turn  a  sharp  corner,  say  to  the  right, 
it  was  noticed  that  the  inner  or  right-hand  wheel  had  to  trav- 
erse a  much  shorter  circular  path  than  the  outer  or  left-hand 
wheel,  and  consequently  had  to  make  less  revolutions  than 
the  left  wheel.  But  the  axle,  which  was  coupled  rigidly  -to 
both  wheels,  opposed  itself  to  this  difference  in  the  amount  of 
rotation,  and  rendered  it  mechanically  impossible  for  the  two 
wheels  to  turn  at  different  speeds.  It  therefore  became  the 
custom  to  stop  the  car  at  a  sharp  corner  and  pull  out  the  pin 
which  fixed  one  of  the  wheels  to  the  axle  (preferably  the  inner 
one  on  the  curve).  (See  Blue  Book  of  Committee  Report  on 
Steam  Carriage  on  Roads,  1831.)  On  removal  of  the  pin  this 
wheel  was  then  no  longer  a  driving  wheel  and  the  axle  could 
freely  rotate  inside  its  hub,  while  the  outer  wheel  was  driven 
by  the  engine  as  before,  and  traversed  its  longer  circular  path 
without  difficulty. 

"Provision  was  doubtless  made  to  prevent  the  loose  wheel 
from  slipping  off  completely  during  this  manoeuver.  When 
th^  corner  had  been  turned,  the  pin  would,  in  the  ordinary 
course,  be  reinstated,  but  it  is  in  human  nature  to  suppose  thaf 


168  MOTORS  AND  MECHANISM 

the  post-boy,  to  whom  this  particularly  greasy  job  was  in- 
trusted, disliked  it  and  shirked  it,  and  was  rewarded  by  find- 
ing that  his  motor  'bus  proceeded  along  its  journey  just  as 
well  without  the  pin  as  with  it. 

•"There  was  a  drawback,  however.  The  power  of  the  engine 
under  these  circumstances  was  entirely  transmitted  by  one  road 
whe'el,  and  on  coming  to  hills  this  wheel  would  skid.  The 
evidence  before  the  Committee  shows  that  these  early  motor- 
ists made  a  practice  of  stopping  near  the  foot  of  steep  hills  to 
rake  their  fires  and  get  up  steam,  thus  affording  an  opportu- 
nity for  replacing  the^pin. 

"It  is  probable  that  turning  to  the  right  was  easier  than 
turning  to  the  left  when  the  right-hand  pin  was  removed,  but 
in  neither  case  was  the  turning  so  hard  as  when  one  wheel  had 
to  be  bodily  scraped  across  the  ground." 

This  plan  of  freeing  one  wheel  foreshadowed  the  plan  (em- 
ployed a  few  years  ago  on  very  small  cars  and  now  being 
resuscitated)  of  employing  a  "free  wheel  clutch"  on  each  of  the 
back  wheels  of  a  car  instead  of  a  differential. 

All  this  impresses .  the  fact  that  every  curve  traced  by  a 
car  requires  the  wheel  on  the  outer  side  of  f  that  curve  to 
rotate  faster  than  it  did  when  the  car  was  going  straight.  The 
wheel  on  the  inside  of  the  curve  obviously  has  to  go  slower  so 
that  in  a  conceivable  case  (on  a  very  sharp  curve)  the  inner 
wheel  might  have  to  be  almost  stationary  (acting  as  a  pivot) 
while  the  outside  one  would  run  round  it  in  a  circular  path. 

Nowadays,  we  recognize  this  fact,  and  to  free  the  wheels 
from  one  another  we  cut  the  axle  in  two  so  that  one  half 
axle  corresponds  to  one  wheel  and  the  other  half  to  the  other 
wheel.  As  both  wheels  must  be  driven,  we  mount  a  bevel 
wheel  (A'  and  B'  of  Fig.  i)  on  each  half  axle,  and  allow  a 
small  portion  of  the  axles  to  project  so  as  to  form  a  center 
for  a  very  simple  device  (Fig.  2),  which  is  placed  between 
them.  We  drive  that  device  round  by  means  of  a  flat  belt  or 
a  chain  or  propeller  shaft,  or  indeed  by  any  mechanical  means, 
and  the  thing  is  done.  We  have  chosen  a  flat  leather  belt  in  the 


MOTORS  AND  MECHANISM  169 

figure  simply  for  convenience.     (The  propeller  shaft  arrange- 
ment will  be  shown  later.) 

This  pulley  has  a  hub  or  center  which  allows  it  to  spin  freely 
on  the  projecting  pieces  A  and  B  of  the  cut  axle  of  Fig.  I. 
From  the  hub  three  or  four  round  spokes  are  used  to  support 
the  belt  pulley's  rim. 


Fig.  I.— A  Bevel  Wheel  fitted  to    Fig.  II.— Belt  Pulley,  arranged  to 
each  half  axle.  run  freely  between  the  two  bevel 

wheels  Al   and  Bl   in  Fig.  I. 

If  it  be  put  in  position  and  driven  by  a  belt  from  the  engine 
it  will  not  drag  the  two  half  shafts  round  with  it  unless  at  least 
one  of  its  spokes  is  fitted  with  a  small  conical  pinion  C.  To 
show  this  clearly  Fig.  3  is  drawn,  which  is  Fig.  2  turned  round 
a  little  more  so  as  to  disclose  the  bevel  wheel.  We  shall  not 


Fig.  III.— Same  Belt  Pulley  Fig.  IV.— Same  Belt  Pulley  fit- 
fitted  with  a  conical  pinion  on  ted  with  pivot  bar  instead  of 
one  spoke.  pinion. 

have  to  introduce  another  bevel  wheel  or  pinion  or  mechanism 
or  complication  of  any  sort.  We  have,  in  fact,  a  complete 
differential  or  "balance  gear"  in  this  very  simple  system,  and 
every  other  kind  of  differential  in  daily  use,  no  matter  how 
complicated  in  appearance,  is  the  same  as  this  and  can  be 
understood  by^  having  understood  this. 


170  MOTORS  AND  MECHANISM 

When  the  belt  pulley  is  turned  round,  it  is  clear  that  either 
(i)  both  half  axles  must  turn,  or  (2)  half  axle  A  must  turn, 
or  (3)  half  axle  B  must  go  round. 

If  there  is  no  friction,  that,  is,  if  no  one  grasps  either  of  the 
half  axles  in  Fig.  i,  both  will  rotate  at  the  same  speed  as  the 
belt  pulley,  so  that  the  central  pinion  might  just  as  well  be 
replaced  by  a  small  pivoted  iron  bar  as  in  Fig.  4.  The  'ends 
of  the  iron  bar  are  cut  on  the  slope,  so  that  they  should  fit 
between  the  teeth  of  the  bevel  wheels  A  and  B,  Fig.  i,  and 
to  prevent  the  bar  from  falling  out,  it  is  pivoted  loosely  on 
to  one  of  the  rqund  pulley  spokes,  as  shown. 

The  two  arms  of  this  iron  bar  are  like  the  two  equal  arms 
of  a  balance.  If  there  be  equal  pressure  or  equal  resistance  to 
motion  on  the  two  arms  of  a  balance,  whether  this  resistance 
be  large  or  small,  the  balance  arm  does  not  turn.  If  there  be 
an  excess  of  resistance  on  one  side,  the  bar  turns  or  yields  on 
that  side.  If  we  call  the  movement  of  the  balance  arm,  on 
which  there  is  the  excess  pressure,  a  backward  movement,  the 
arm  on  the  other  side  moves  forward  by  an  equal  amount, 
until,  if  the  excess  pressure  continues,  the  balance  arm  slips 
out  from  between  the  teeth  of  the  two-side  bevels.  This  gives 
us  tlje  reason  why  a  little  pinion,  as  in  Fig.  3,  is  used  instead 
of  a  bar.  Its  action  is  exactly  the  same  as  the  bar,  but  it 
has  this  advantage  over  the  pivoted  bar  on  the  balance  arm, 
that  when  a  large  "out-of-balance  pressure"  is  exerted  and 
maintained,  another  pair  of  teeth  come  into  engagement  with 
the  teeth  of  bevel  wheels  A  and  B. 

Let  us  now  consider  the  whole  appliance  in  action.  When 
the  car  is  traveling  forward,  driven  by  the  belt  pulley,  the 
pressures  on  the  two  arms  of  the  bar  are  equal  to  one  another. 
When,  however,  the  steering  wheels  are  deflected  to  one  side, 
it  is  clear  without  any  mathematical  demonstration  that  the 
car  no  longer  rolls  forward  as  easily  as  if  all  the  wheels  were 
pointing  in  the  same  direction  as  that  in  which  the  car  is 
traveling.  The  steering  wheels  therefore  introduce  a  resistance 
to  forward  motion,  which  may  be  slight  or  may  be  great, 
according  to  the  amount  of  deviation  from  a  straight  course, 


MOTORS  AND  MECHANISM  171 

and  this  resistance  is  not  the  same  on  the  two  sides  of  the 
car.  There  is,  in  fact,  a  greater  resistance  to  forward  move- 
ment from  that  steering  wheel  which  is  on  the  inner  side  6f  the 
curve.  On  a  motor  car  the  steering  gear  is  so  contrived  that 
whichever  front  wheel  is  the  inner  wheel  (and  therefore  runs 
round  the  smaller  radius  of  a  curve)  is  always  more  deflected 
than  the  outer  wheel.  To  a  person  who  has  never  owned  a 
motor  car  the  same  fact  can  easily  be  brought  home  by  a 
simple  experiment  with  any  wagon  or  four-wheeled  carnage. 
Turn  the  front  wheels  of  the  wagon  round  through  a  sharp 
angle,  and  then  attempt  to  push  the  wagon  by  hand  from"  the 
back  wheels.  First  try  pushing  at  a  spoke  of  the  inner  back 
wheel,  and  then  try  pushing  a  spoke  of  the  outer  back  wheel. 
It  will  be  found  that  when  the  outer  back  wheel  is  being 
pushed  the  wagon  is  moved  very  much  more  easily. 

In  other  words,  an  excess  of  resistance  is  offered  by  the 
inner  back  wheel,  that  is,  the  wheel  which  is  on  the  inner  side 
towards  which  the  steering  is  deflected.  If  the  belt  pulley  of 
Fig.  3  or  Fig.  4  is  driven  round  by  the  engine,  exerting  con- 
tinually a  certain  effort,  that  effort  is  always,  and  under  all 
circumstances,  divided  into  exactly  two  equal  parts  by  the 
balancing  effect  of  the  pinion  (or  the  lever  arm  of  Fig.  4), 
but  whichever  half  axle  offers  the  less  resistance  obviously 
turns  more  easily  precisely  in  proportion  as  the  resistance  is 
less.  So  the  differential  gear  performs  its  function,  and  drives 
the  outer-driven  wheel  to  turn  more  than  the  inner  wheel,  and 
this  difference  is  the  greater  the  sharper  the  curve. 

A  Second  Explanation. 

As  one  man's  difficulty  in  understanding  a  mechanism  is 
not  the  same  as  another's,  so  it  may  be  useful  to  some  readers 
to  have  a  totally  fresh  and  independent  explanation  from  a 
different  standpoint.  Here  are,  therefore,  two  illustrations,  and 
some  very  lucid  text  which  originally  appeared  in  The  Horse- 
less Age. 

In  Fig.  5  A  and  B  are  two  racks — that  is,  straight,  rec- 
tangular bars  with  teeth  cut  on  them.  These  racks  are  rest- 


172 


MOTORS  AND  MECHANISM 


ing  on  the  floor  and  free  to  move  vertically  in  guides.  They 
are  loaded  down  by  weights  W,  W1.  Between  the  racks  is 
interposed  a  pinion,  which  rotates  round  E,  supported  in  the 
yoke  D.  If  a  lifting  force  be  applied  to  the  yoke  D,  in  the 
direction  of  the  arrow,  and  the  weights  W,  W1  be  equal,  as 
well  as  the  weights  of  the  two  racks,  and  their  friction  in 
the  guides,  then  the  two  racks  will  be  lifted  together  and 
the  pinion  will  not  turn,  but  will  remain  in  the  same  relative 
position  to  the  racks. 

If  we  add  to  the  weight  W1  another,  W2,  and  again  apply  a 
lifting  force  to  the  yoke,  then  the  resistance  to  motion  of  rack 


Fig.  V. — Model  to  explain  differential  gear. 

B  being  greater  than  the  resistance  of  rack  A,  B  will  remain 
stationary.  A  will  rise  and  the  pinion  will  turn  about  its  shaft 
E.  This  is  under  the  supposition  that  the  additional  weight 
W2  more  than  counterbalances  the  friction  of  the  pinion  at 
its  shaft  and  at  the  teeth.  We  have  then  a  differential  motion, 
the  same  as  in  a  differential  gear,  which  is  brought  about  by 
increasing  the  resistance  to  motion  of  one  of  the  racks. 

In  a  differential  gear  of  the  bevel  gear  type  the  two  racks 
in  the  illustration  (Fig.  5)  are  represented  by  the  two  side 
bevel  gears  (Fig.  6)  and  the  pinion  C  is  a  bevel  pinion,  of 
which  three  or  more  are  usually  provided.  The  power  is  again 


MOTORS  AND  MECHANISM 


173 


applied  at  the  shaft  of  the  pinion,  to  which  in  the  figure  a 
handle  is  shown  attached,  but  which  in  practice  is  connected 
with  a  sprocket  or  chain  wheel.  As  long  as  the  resistance  to 
motion  of  the  two  bevel  wheels  A  and  B  is  equal,  the  pinion 
C  will  not  turn  on  its  center  D,  but  wall  simply  rotate  round  the 
center  of  the  shafts  F  and  G,  which  are  the  two  halves  of  the 
driving  axle,  and  will  carry  the  bevel  wheels  A  and  B  along 
with  it,  the  two  (A  and  B)  thus  rotating  at  the  same  speed. 
Now,  suppose  that  the  resistance  to  rotation  of  B  becomes 
greater.  This  occurs  when  the  steering  wheels  are  turned 
to  that  side.  Then  pinion  C  will  begin  to  revolve  round  its 


Fig.  VI.— Model  of  Bevel  Differential. 

shaft  and  allow  bevel  wheel  A  to  turn  faster  than  bevel  wheel 
B.  These  two  bevel  wheels  are  connected  through  the  two 
half-axles  to  the  driving  wheels,  and  hence,  if  these  bevel 
wheels  turn  -at  different  speeds,  the  driving  or  road  wheels 
do  also. 

In  the  crypto  type  of  differential  many  makers  utilize  flat 
gear  wheels  instead  of  bevel  wheels,  because  they  can  be  more 
accurately  cut,  and  from  that  point  of  view  this  form  of  differ- 
ential is  an  advantage.  Purchasers  are  prone  to  pay  insuf- 
ficient heed  to  the  differential  being  of  good  make  and  free 
running.  It  is  probable  that  if  they  realized  what  a  differ- 
ence a  good  differential  may  make  to  the  life  of  the  driving 
wheel  tires,  they  would  alter  their  attitude  in  this  respect. 


174  MOTORS  AND  MECHANISM 

Although  we  have  now  described  everything  in  a  differential, 
we  must  not  forget  that  in  ordinary  parlance  the  term  is 
erroneously  used  to  include  a  great  deal  more,  namely,  every- 
thing contained  in  the  differential  case. 

If,  in  place  of  the  belt  drive  employed  in  the  example  (Fig. 
3),  another  mechanical  drive,  namely,  a  bevel  drive,  were 
used,  the  addition  of  the  external  bevel  wheel  and  its  pinion 
would  lend  to  the  gear  the  appearance  of  Fig.  4.  But  we 
must  not  be  led  to  suppose  that  this  driving  gear  is  essentially 
part  of  the  differential.  It  has  nothing  to  do  with  it.  It  is 
merely  placed  in  a  case  in  close  proximity  to  the  differential. 
Lastly,  it  may  be  said  that  instead  of  one  pinion  C  being 


Fig.   VII. — Complete   Differential    showing   bevel,    drive   and   pulley. 

placed  on  only  one  spoke,  it  is  usual  to  place  two  or  three 
such  pinions  all  performing  exactly  the  same  function  on  the 
other  spokes,  and  further,  if  the  drive  shown  in  Fig.  7  is 
adopted,  the  side  thrust  due  to  this  form  of  drive  must  be 
taken  by  thrust  bearings,  which  are  usually  ball  bearings. 
All  these  extra  details  are  shown  in  the  completed  figure  of  an 
actual  differential  gear  (Fig.  8). 

Further  Effects  of  the  Differential — If  the  car  be  jacked  up 
so  that  both  driven  wheels  are  clear  of  the  ground  and  if  the 
engine  be  run  so  as  to  drive  the  wheels  round,  they  will  turn 
at  the  same  speed  if  they  are  equally  free  from  friction  and  if 
the  brake  bands  are  clear.  If  now  one  wheel  be  stopped  by 
hand,  the  other  will  be  found  to  rotate  at  double  the  previous 
speed. 


MOTORS  AND  MECHANISM  175 

If  the  engine  be  stopped  and  the  brake  be  applied  to  the 
propeller  shaft  so  as  to  lock  it,  it  will  be  found  that  if  one 
of  the  driving  wheels  be  turned  forward  by  hand,  the  other 
wheel  will  rotate  backward  by  a  precisely  equal  amount,  and 
at  the  same  speed. 

The  knowledge  of  both  these  facts  is  important  to  the  driver 
of  a  car  because  of  its  bearing  upon  the  best  way  to  avoid 
skidding,  side-slipping,  and  indirectly  the  excessive  wear  of 
tires. 

In  the  course  of  ordinary  straightforward  running^  the  differ- 
ential is  always  slightly  in  action,  because  the  adhesion  of  the 
two  driving  wheels  is  never  exactly  the  same.  That  is  (i) 
owing  to  the  uneven  distribution  of  the  weight  of  the  pas- 
sengers, or  because  the  car  itself  never  weighs  exactly  the 


THRUSTBEAKING 


KEY  FOR  FIXING 
SPROCKETS 


Fig.  VIII. — Complete  Differential  as  used  on  car. 

same  amount  on  both  driving  wheels ;  (2)  owing  to  the  sur- 
face of  the  road  being  invariably  different  to  the  two  wheels 
to  a  slight  degree.  Thus  either  a  road  depression  is  under  one 
wheel  or  an  excrescence  is  under  one  wheel  or  a  .more  slippery 
surface  is  under  one  wheel. 

Now,  no  matter  what  difference  of  adhesion  there  may 
be  between  the  two  wheels  and  the  ground,  the  differential 
provides  that  no  more  effort  can  be  exerted  on  the  wheel  which 
has  the  more  adhesion  than  on  the  wheel  which  has  the  least. 
Thus  the  forward  effort  on  the  car  can  never  be  more  than 
that  due  to  twice  the  smaller  adhesion,  and  further  as  the 
efforts  from  the  two  wheels  are  always  equal,  the  forward 
effort  on  the  car  is  always  applied  to  the  car,  as  it  were,  from 
the  center  of  the  back  (or  driving)  axle.  If  the.  wheels  were 
keyed  solidly  to  a  solid  axle  without  differential,  the  wheel 
which  had  the  best  adhesion  with  the  ground  would  obviously 
transmit  the  larger  part  of  the  forward  push,  so  that  the  result- 


176  MOTORS  AND  MECHANISM 

ant  push  or  effort  from  both  wheels  would  not  be  at  the  center 
of  the  back  axle,  but  nearer  to  one  side,  the  side  of  better 
adhesion. 

This  then  is  an  advantage  of  the  differential  when  the  car 
is  in  use  on  the  road  in  many  cases,  but  in  some  of  the  situa- 
tions which  arise  in  the  course  of  traveling  by  road,  this  very 
merit  presents  certain  complementary  disadvantages.  Thus 
if,  as  often  happens,  one  driving  wheel  has  good  adhesion, 
while  the  other  is  on  very  slippery  ground,  it  is  evident  that 
the  differential  prevents  the  wheel  which  has  goc  \  adhesion 
from  driving  the  car  forward  with  any  better  effect  than  if 
both  wheels  were  on  the  same  slippery  piece. 

The  good  adhesion  of  the  wheel  which  is  on  good  ground  is, 
of  course,  capable  of  preventing  side-slip  of  the  car,  but  it  is 
not  capable  of  being  utilized  for  forward  propulsion  beyond  the 
amount  which  is  possible  to  the  other  wheel  on  slippery 
ground. 

In  other  words,  a  car  which  had  a  solid  axle  without  differ- 
ential should  travel  forward  more  quickly  on  a  surface  of 
which  some  parts  were  more  slippery  than  others,  because  it 
would  invariably  be  able  to  utilize  to  the  full  for  forward 
effort  whichever  wheel  presented  the  best  adhesion,  plus  the 
small,  but  still  not  negligible  effort  on  the  other  wheel.  This 
advantage,  and  a  certain  superiority  in  avoiding  side-slip, 
would  also  accrue  to  a  car  fitted  with  two  "free  wheels." 


GEAR  EFFICIENCY. 

Users  of  cars  cannot  fail  to  be  interested  in  the  following 
figures  of  efficiency  for  various  kinds  of  gear  road  wheels  and 
tires.  They  are  reported  by  a  European  authority  from  electric- 
al experiments  by  Mr.  R.  Lacau. 

"As  an  instrument  of  research  electricity  is  invaluable  in 
this  as  in  every  other  industrial  field,  because  it  allows  of  the 
use  of  accurate  measuring  and  recording  instruments,  which 


MOTORS  AND  MECHANISM 


177 


eliminate  personal  error  and  enable  a  whole  laboratory  to  be 
transported  readily  to  the  scene  of  the  test,  even  on  a  motor 
car.  One  of  the  most  striking  results  thus  measured  is  per- 
haps the  high  efficiency  established  for  a  well  greased  roller 
chain  in  spite  of  its  exposure  to  air  and  dust.  Ninety-four 
per  cent  of  the  energy  put  into  a  roller  chain  in  actual  use  on  a 
car  re-appeared  as  energy  on  the  back  sprocket,  and  whereas 
a  pair  of  steel  spur  wheels  similarly  exposed  only  returned  90 
per  cent.  These  were  the  figures  for  new  apparatus.  When 


jr. 


I.  The  most  efficient  drive.    No  gear  reduction.    Electric  motor  on  the  axle. 
IL  The  second  most  efficient  drive.    One  chain  reduction.    The  motor  and  road  whefllfl 
rotating  in  the  same  plane,  94  per  cent,  when  new,  92  per  cent,  when  worn.    - 

the  chains  were  worn,  the  number  fell  to  92  per  cent,  but 
when  the  spur  wheels  were  worn  the  number  fell  to  80  per 
cent,  and  this  is  where  the  important  difference  comes  in  from 
the  point  of  view  of  the  power.  Spur  wheels,  it  will  be  urged, 
are  not  generally  run  exposed  to  the  dust  and  air,  but  in 
gear-boxes  full  of  oil.  .  Under  this  condition  92  per  cent  of 
the  energy  put  into  the  first  wheel  was  obtained  from  the 
second  when  all  was  new,  and  only  90  per  cent  when  worn,  so 
that  even 'the  new  spur  wheels  cased  in  were  only  about 

12 


178 


MOTORS  AND  MECHANISM 


equal  in  efficiency  to  the  worn  roller  chain  exposed  to  the 
dust  and  air. 

"It  is  not  always,  however,  that  a  plain  spur  wheel  is  to  be 
contrasted  with  a  chain.  It  is  sometimes  the  much  less  effi- 
cient apparatus,  a  bevel  spur  wheel,  that  must  be  compared, 
and  such  wheels  well  cased,  running  in  oil  and  brand  new, 
afforded  88  per  cent,  or  when  old  82  per  cent  efficiency  only. 
The  bevel  wheel  arrangement  is  in  the  case  of  many  types  of 
car  associated  inevitably  with  the  Hooke  coupling  or  universal 


III.  Two  reductions  vf  speed  by  chain,  88  per  cent,  when  new,  84  per  cent,  whe  n  worn. 
IT.  ,,  »  •>  but  power  taken  round  a  right  angle,  79  per 

cent  when  new,  65  per  cent  when  worn. 

joint.  It  is  not  always  appreciated  that  this  ingenious  device 
wastes  power.  It  does  not  waste  much,  but  even  when  new 
it  does  waste  some,  and  if  100  H.P.  is  put  in  at  one  end  of  the 
shaft  only  96  per  cent  can  be  got  out  at  the  other  under  ordi- 
nary road  conditions.  It  will  be  understood  in  this,  which 
appears  like  a  tirade  against  bevel  driven  live  axle  cars,  that 
nothing  of  the  sort  is  intended.  Such  cars  may,  if  well  con- 
structed, be  far  superior  to  certain,  or  even  all  existing  chain- 
driven  cars,  but  for  the  sake  of  the  present  investigation  atten- 
tion must  be  directed  to  one  point  at  a  time,  and  that  one 


MOTORS  AND  MECHANISM  179 

point  for  the  moment  being  efficiency  of  transmission,  there 
is  no  question  but  that  the  chain  is  shown  by  experiment  to 
be  superior. 

"In  view  of  the  great  demand  for  very  silent  drives,  even 
for  auxiliary  plant,  such  as  pumps,  magnets,  etc.,  the  steel 
pinion  and  fiber  ring,  and  the  rawhide  pinion  with  cast  iron 
rings  have  an  interest,  inasmuch  as  it  is  perfectly  legitimate 
for  an  intending  purchaser  to  ask  himself  whether  he  would 


iz. 


7.  Three  reductions  of  «i>eed,  one  being  right-angled  drive,  74  percent,  when  new,  69 

per  cent,  when  worn. 

VI.  Four  reductions  of  speed,  one  being  right-angled  drive,  07  per  cent,  when  new,  48 
per  cent,  when  worn* 

prefer  to  consume  a  little  more  fuel  and  travel  more  quietly, 
and  if  that  be  all  that  enters  into  the  problem  he  would  prob- 
ably consider  it  wise  to  prefer  the  quietude  and  pay  the  price. 
The  efficiencies  of  these  two  silent  combinations  appear  to  be 
in  both  cases  88  per  cent  with  new  gear  and  about  80  per 
cent  with  worn. 

"It  must  not,  however,  be  assumed  that  because  it  is  easier 
to  make  the  fiber  and  rawhide  combinations  more  silent  than 
the  plain  steel  ones,  that  in  certain  conditions  it  is  not  pos- 


180  MOTORS  AND  MECHANISM 

sible  to  approach  to  the  same  degree  of  quietude  at  a  little 
more  expense  in  the  accurate  gear  cutting  of  steel  wheels. 

"Road  Wheels — Many  owners  have  believed  the  tractive 
resistance  of  solid  tires  to  be  less  than  that  of  pneumatics 
under  certain  conditions.  Not  having  been  able  to  bring  any- 
thing but  roughly  approximate  experiments  to  support  the 
view  they  were  glad  to  have  Mr.  Lacau's  confirmation  by 
experiment  of  a  careful  kind  to  show  that  on  the  electrical  car 
on  which  the  tests  were  taken  at  13  miles  an  hour  on  good  dry 
macadam,  free  from  dust,  the  tractive  pull  per  ton  was  33 
Ibs.  to  40  Ibs.  with  solids ;  44  Ibs.  to  53  Ibs.  with  90  mm.  pneu- 
matics; 53  Ibs.  to  62  Ibs.  with  the  same  pneumatics  partly 
inflated;  and  64  Ibs.  to  71  Ibs.  with  120  millimeter  pneu- 
matics on  the  same  car." 


MOTORS  AND  MECHANISM  181 


CHAPTER  XL 
SPUR  OR  TOOTHED  GEAR. 

Gear,  Spur — Gearing  composed  of  spur  wheels,  the  latter 
being  the  ordinary  form  of  cogwheels.  The  cogs  are  radial 
and  peripheral,  and  are  adapted  to  engage  countershaft  cogs 
on  another  wheel.  The  pitch-lines  of  the  driving  and  the 
driven  wheels  are  in  one  plane.  See  Gear  or  Gearing. 

Spur  wheels  or  toothed  gear  wheels  are  liable  to  damage 
from  the  following  causes: 

(1)  From  being  overloaded,  or  asked  to  transmit  an  effort 
greater  than  the  engaging  teeth  are  jointly  strong  enough  to 
bear,  for  example,  when  a  countershaft  brake  is  used  too  vio- 
lently. 

(2)  From  being  mounted  on  engaging  wheels  whose  axles 
are  badly  aligned  or  at  the  wrong  distance  apart. 

(3)  From  being  badly  cut,  or  cut  to  a  bad  profile. 

(4)  From  being  badly  handled  by  the  driver  in  one  of  four 
ways: 

(a)  Allowed  to  drive  when  only  in  partial  engagement. 

(b)  Allowed  to  take  up  the  drive  with  a  blow  or  shock, 

instead  of  taking  up  the  pressure  gently. 

(c)  Brutally  forced  into  engagement. 

(d)  Being  neglected  as  to  lubrication. 

All  these  cases  are  really  methods  of  obtaining  an  overload 
on  the  teeth. 


182  MOTORS  AND  MECHANISM 

Alignment — Thus  in  (2)  the  effect  of  bad  alignment  is  that 
the  whole  pressure  due  to  the  transmitting  the  effort  of  the 
engine  comes  upon  an  edge  of  the  teeth  instead  of  acting 
upon  the  whole  width,  thus  overloading  the  acting  edge.  Bad 
alignment  after  an  overhaul  in  an  amateurish  repair  shop  is 
the  most  likely  trouble,  and  one  of  the  hardest  for  an  un- 
skilled owner  to  detect. 

Meshing — It  is  fairly  easy  to  know  in  a  general  way  if  spur 
wheels  are  not  meshing  properly,  that  is  to  say,  in  more  tech- 
nical terms,  if  the  pitch  circles  are  not  touching  one  another. 
To  begin  with,  the  gear  will  be  noisy.  If  the  meshing  be  too 


Fig.  1— Showing  Overall  and  Pitch  Circles. 

deep  the  tips  of  the  teeth  on  one  wheel  will  penetrate  so  far 
into  the  spaces  on  the  other  wheel  that  the  clearance  marked 
C  on  Fig.  i  will  not  exist,  and  the  ends  of  the  teeth  will  be 
continually  in  compression.  The  obvious  general  rule,  how- 
ever, is  this:  Measure  the  distance  between  the  centers  of 
the  engaging  spur  wheels  and  divide  this  into  two  lengths 
in  the  ratio  of  the  number  of  teeth  in  each  wheel.  These  two 
lengths  are  the  radii  of  the  pitch  circles,  and  the  pitch  circles 
if  described  on  the  wheels  would  cut  each  tooth  at  a  little, 
outside  of  the  middle  of  its  engaging  face.  When  two  teeth 
are  in  full  engagement,  the  line  from  center  to  center  of  the 
wheels  passes  through  the  point  of  contact  of  the  teeth,  and 
so  do  both  the  pitch  circles.  If  teeth  mesh  badly,  whether  too 


MOTORS  AND  MECHANISM  183 

deeply  or  too  little,  there  is  rubbing  and  crushing  of  the  sur- 
faces and  loss  of  efficiency,  particularly  with  cycloidal  teeth. 

Shape  of  Teeth — In  (3)  the  effect  of  a  tooth  being  a  bad 
shape  is  that  even  though  the  whole  width  of  surface  is  op- 
erative the  root  or  other  part  of  the  tooth  has  been  made  too 
thin  for  the  pressure  to  be  transmitted ;  it  is  therefore  over- 
loaded and  snaps.  Involute  teeth  are  preferable  to  cycloidal 
in  the  gear-box. 

Partial  Engagement — In  (4)  if  a  careless  driver  leaves  the 
speed  lever  in  an  intermediate  position  between  the  notches, 
.or  if  the  quadrant  which  carries  the  notches  is  strained  over 
by  rough, usage,  only  a  fraction  of  the  width  of  the  tooth  is 
operative  and  overloading  of  that  fraction  occurs,  so  that 
either  a  piece  chips  off  or  the  metal  crushes'  and  flows  gener- 
ally so  as  to  make  a  burr  on  the  edge  of  the  tooth.  If  a  piece 
chips  off  there  is  grave  risk  of  much  expensive  damage  re- 
sulting from  the  piece,  even  if  quite  small,  getting  jammed 
between  another  pair  of  teeth  and  snapping  either  one  or 
other  off.  The  freshly  broken  tooth  may  then  chance  to  drop 
between  two  other  wheels  rotating  in  engagement,  and  it  will 
ruin  them  also,  whether  or  not  they  be  transmitting  any 
power.  This  possibility  of  damage  being  done  to  gear  wheels 
which  are  rotating  idly,  by  the  accidental  intrusion  of  for- 
eign matter  such  as  a  flynut  belonging  to  the  lid  of  the  box, 
is  a  slight  drawback  to  the  type  of  gear-box  which  employs 
such  idly  rotating  wheels,  apart  from  the  objection  to  the 
noise  and  the  waste  of  power.  The  latter,  however,  need  not 
be  important  if  the  gear-box  be  fitted  with  ball  or  roller  bear- 
ings. 

Fierce  Clutch  let  in  badly — A  cause  of  damaged  gear  wheels 
is  sometimes  the  accident  by  which  one's  foot  slips  off  the 
clutch  pedal.  If  it  be  very  fierce,  and  the  engine  running  fast 
while  the  car  is  nearly  stationar}%  a  considerable  jar  results. 
It  is  true  that  the  factor  of  safety,  or  the  margin  of  strength 
of  the  teeth,  ought  to  be  sufficient  to  allow  for  all  such  eventu- 
alities as  may  legitimately  occur  to  a  careful  driver,  but  the 
size  and  weight  of  parts  is  very  closely  cut  in  motor  cars, 


184  MOTORS  AND  MECHANISM 

and  the  design  is  rightly  made  as  close  to  the  safe  limit  as 
possible.  A  slippery  pedal  should  be  roughed  at  an  early  op- 
portunity. 

Noisy  Toothed  Wheels — The  teeth  of  gear  wheels  cannot 
be  engaging  each  other  properly  if  there  is  much  noise.  This 
incorrectness  (if  not  in  the  original  design)  may  be  due : 

(1)  To  warping. 

(2)  To  wear. 

(3)  To  bad  alignment  of  the  axes. 

(4)"  To  bad  distancing  of  the  wheel  centers,  especially  with 
cycloidal  teeth. 

(5)  To  sliding  wheels  badly  centered  on  a  square  shaft. 

Warping  takes  place  in  manufacture  during  the  process  of 
hardening  the  surface  of  mild  steel  teeth.  The  expense  of 
grinding  teeth  after  they  have  been  hardened  is  so  great  that 
it  is  often  avoided  by  the  maker,  and  the  hardened  teeth  are 
matched  with  one  another  after  hardening  by  the  process  of 
trial  and  error  till  a  silent  pair  is  found. 

It  is  well  to  remember  that  silent  gears  on  a  new  car  are 
not  necessarily  a  sign  of  perfection  of  the  gears,  because  ob- 
viously if  the  hardening  process  has  been  simply  omitted  there 
will  have  been  no  warping,  and  the  truly  cut  tooth  profiles 
(machine  cut  with  great  accuracy  in  most  cases)  will  not 
make  any  noise  till  the  absence  of  hardening  has  been  re- 
vealed by  the  rapid  wear.  As  a  test  of  hardening,  one  can- 
not cut  the  face  of  a  hardened  mild  steel  tooth  with  a  file  save 
with  difficulty,  and  the  roughness  cf  the  file  gets  polished  in 
the  attempt. 

Latterly,  and  in  some  of  the  very  finest  cars,  certain  pe- 
culiar steels  with  special  alloys  are  used,  which  are  suffi- 
ciently hard  in  themselves,  and  very  tough  and  strong.  These 
steels  do  not  require  to  be  case-hardened,  and  though  they 
have  not  got  sufficient  hardness  to  pass  the  file  test  they  are 
well  able  to  stand  up  against  the  wear  of  the  gear-box. 

This  fact  is  mentioned  to  prevent  conclusions  being  arrived 
at  too  hastily  by  the  inexpert.  In  cases  where  legal  action 
is  being  taken  on  the  ground  of  alleged  bad  work  and  ma- 


MOTORS  AND  MECHANISM  185 

terials,   analysis   or  full  mechanical  test  should  be   made  of 
the  steel. 

Noise  of  Gear  Changing — The  noise  of  gear  changing  must 
not  be  confused  with  the  noise  previously  alluded  to  made  by 
the  gears  after  the  change  has  been  effected.  Gear  changing 
with  "clash"  gear  of  the  sliding  type  is  noisy  when  the  sides 
of  the  teeth  which  have  to  be  pushed  past  one  another  are  not 
rounded  off,  or  when  the  rounded  sides  have  been  bruised  by 
the  driver  using  too  much  "force  in  effecting  the  change,  or 
by  the  driver  attempting  to  change  without  keeping  the  clutch 
pedal  fully  depressed. 

Even  when  the  clutch  pedal  is  fully  depressed  it  is  im- 
portant to  remember  that  the, light  or  inner  part  of  the  clutch 
has  a  certain  inertia  of  its  own  and  tends  to  continue  revolv- 
ing after  it  has  left  contact  with  the  fly  wheel.  It  is  only 
when  this  movement  has  reached  a  certain  value  that  the  ideal 
condition  for  sliding  the  gear  occurs.  That  condition  occurs 
when  the  teeth  which  are  coupled  to  the  road  wheels  move  at 
the  same  speed  as  the  teeth  which  are  driven  round  by  the 
inertia  of  the  clutch  and  are  about  to  be  thrust  between  them. 

To  facilitate  the  getting  of  this  condition  during  the  driv- 
ing of  the  car  a  small  brake  pad  is  often  arranged  near  the 
back  of  the  clutch,  so  that  when  the  clutch  pedal  is  fully  de- 
pressed the  clutch  cone  (male  part)  comes  into  frictional  con- 
tact with  the  brake  pad. 

A  better  arrangement  still  is  provided  by  some  designers, 
wHo  make  the  male  part  of  the  clutch  and  the  gears  to  which 
it  is"  connected  of  such  small  size  and  light  weight  that  they 
have  but  little  inertia  and  therefore  easily  take  up  any  speed 
or  change  of  speed  which  may  be  impressed  on  them  by  the 
gear  wheels  they  are  lightly  put  into  contact  with. 

Broken  Toothed  Wheel — If  it  is  not  convenient  to  get  into 
touch  with  the  maker  of  the  car  (as  often  happens  when  one 
is  in  a  distant  state)  the  correct  replacement  of  a  broken  gear 
wheel  is  a  difficult  matter.  It  will  be  facilitated  by  sending 
to  the  best  local  gear  cutter  either  a  broken  part  or  a  "rub-, 
bing"  on  paper  made  from  the  profile,  of  the  tooth,  provided 


186 


MOTORS  AND  MECHANISM 


such  profile  be  not  rounded  off,  accompanied  by  a  dimensioned 
sketch  of  the  gear  wheel  and  stating  the  number  of  teeth.  One 
tooth  may  with  advantage  be  roughly  sketched,  and  the  di- 
mensions carefully  taken  and  indicated  on  the  sketch. 

The  dimensions  given  must  be  (referring  to  Fig.  i)  as  fol- 
lows: 

Di.    The  diameter  of  the  overall  circle,  or  of  the  "pin- 
ion blank." 

Dn.    The  diameter  of  the  -wheel  i    the  pitch  line. 
Dm.    The  diameter  of  the  circle  at  the  root  of  the 
teeth. 

H.    The  height — {that  is,  the  working  height  inclusive 
of  the  clearance  C). 

(th)  The  thickness. 

It  will  be  seen  that  the  essential  thing  to  find  is  the  pitch- 
line  diameter. 
The  depth  and  width  of  the  tooth  must  also  be  given. 


Fig.  2 — Showing  where  to  measure  the  Pitch  Circle. 

For  bevel  wheels  the  same  dimensions  are  required  taken 
from  the  thick  end  of  the  tooth,  the  pitcl^  circle  being  as  shown 
in  Fig.  2.  The  angle  of  the  cone  must  also  be  given.  This  is 
the  angle  subtended  by  the  pitch  circle  (Fig.  2). 

The  bevel  in  live-axle  cars  is  the  toothed  wheel  which  is 
most  frequently  weak  in  design,  or  at  least  cut  too  fine  as  to 
its  margin  of  safety 


MOTORS  AND  MECHANISM  187 


CHAPTER  XII. 
SHAFTS. 

Shafts — A  shaft  in  machinery  is  a  revolving  member  which 
transmits  power.  Shafts  are  of  different  types  to  suit  the  dif- 
ferent conditions  under  which  they  work.  The  shafting  in 
a  machine  shop  affords  a  good  example  of  the  simplest  form. 
A  shaft  used  for  this  purpose  consists  of  a  long  length  of 
plain  cylindrical  steel  upon  which  pulleys  are  mounted  which 
drive  the  machines,  or  other  shafts,  by  means  of  belts.  The 
principal  shafts  used  in  motor-car  construction  are  as  follows : 

Camshaft — A  revolving  shaft  carrying  cams.  In  the  case 
of  motor  cars  the  term  is  applied  to  the  half-speed  or  two-to- 
one  shaft  which  carries  the  cams  operating  the  valves  or  low 
tension  magneto  mechanism  for  breaking  contact. 

In  a  typical  camshaft  for  a  four-cylinder  engine  the  shaft  is 
turned,  with  its  cams  and  collars,  from  one  solid  piece  of  steel,. 
all  the  bearing  and  wearing  surfaces  being  ground  true  after 
the  shaft  is  hardened.  There  is  a  tapered  end,  to  which  is 
fitted  any  appliance  which  has  to  be  driven  by  the  cam  shaft, 
such  as  the  pump  or  fan.  At  the  other  end  is  the  gear  wheel, 
which  is  driven  by  a  pinion  on  the  engine  shaft  half  its  size, 
and  so  drives  the  camshaft  at  half  the  speed  of  the  engine. 
On  the  inside  of  the  gear  wheel  are  two  lugs,  to  which  the 
governor  balls  are  pivoted.  Two  collars  solid  with  the  shaft 
locate  it  in  its  bearings  and  prevent  it  moving  endways.  In 
the  center  of  the  shaft  is  a  helical  or  skew  gear  wheel  which 
drives  a  similar  wheel  on  a  vertical  shaft,  at  the  top  of  which 
is  mounted  the  contact  maker.  The  cams  are  eight  in  num- 
ber, four  of  them  operating  the  inlet  valves  and  four  the 
exhaust  valves. 


188  MOTORS  AND  MECHANISM 

The  reason  for  calling  the  camshaft  a  "half-speed  shaft" 
is  that  the  shaft  is  driven  by  means  of  gearing  at  half  the 
speed  of  the  crankshaft,  as  described  under  Internal  Com- 
bustion Engine.  That  is  to  say,  for  every  two  revolutions  of 
the  crankshaft  the  camshaft  only  makes  one.  It  is  only  nec- 
essary to  operate  each  valve  once  during  every  two  revolu- 
tions of  the  crankshaft,  and  this  method  of  gearing  is  em- 
ployed to  lift  the  valve  at  the  correct  time.  The  camshaft 
is  also  used  to  vary  the  lift  of  the  valves,  or  to  give  half  com- 
pression in  the  cylinder  head.  In  the  case  of  low  tension  mag- 
neto ignition  the  contact  breaker  is  operated  by  cams  in  the 
same  manner.  Also  the  ordinary  contact  maker  or  make-and- 
break  device  for  high  tension  ignition  is  usually  driven  by  the 
cam-shaft. 

Cardan  Shaft — Where  two  shafts- are  not  in  line  with  one 
another,  or  when  their  position  in  relation  to  one  another 
varies,  and  one  has  to  drive  the  other,  an  arrangement  called 
an  arbor  or  cardan  shaft  is  used  to  connect  the  two.  This 
shaft  is  fitted  with  universal  joints  at  each  end,  so  that  it  can 
adapt  itself  to  the  inequalities  of  the  drive.  Cardan  shafts 
are  also  used  to  transmit  power  frohi  the  gear  box  to  the  rear 
live  axle,  and  are  then  sometimes  referred  to  as  propeller 
shafts. 

Countershaft — An  intermediate  shaft,  taking  power  from 
one  shaft  and  transmitting  it  to  another  by  means  of  chains, 
gearing  or  belts.  The  term  is  usually  applied  to  the  shaft 
which  crosses  the  car  and  carries  the  chain  sprockets  on  its 
extreme  ends,  being  driven  by  means  of  bevel  wheels  from  the 
gear  box.  The  term  is  also  applied  to  the  secondary  or  lay 
shaft  in  the  gear  box.  Also  called  Jackshaft  or  Cross  Shaft. 
See  Secondary  Shaft. 

Crankshaft — The  shaft  which  receives  the  impulses  of  the 
piston,  the  cranks  converting  the  reciprocating  motion  of  the 
pistons  into  rotary  motion.  The  throw  of  the  crankshaft  is 
the  distance  between  the  center  of  the  crankshaft  and  the 
center  of  the  crank  pin,  this  distance  being,  of  course,  half  the 


MOTORS  AND  MECHANISM  189 

stroke  of  the  piston.  The  power  from  the  crankshaft  is  usu- 
ally transmitted  to  the  gear-box  via  the  clutch. 

Cross  Shaft — A  shaft  which  transmits  power  from  another 
shaft  while  its  axis  is  at  an  angle  to  the  axis  of  .the  shaft 
driving  it.  It  is  a  term  usually  applied  to  the  countershaft 
of  a  car. 

Engine    Shaft — See    Crankshaft. 

Flexible  Shaft — A  means  of  connection  between  two  mem- 
bers capable  of  transmitting  power  from  one  to  the  other 
through  any  angle  or  angles  whatever.  .It  usually  takes  the 
form  of  a  tubular  spiral  through  the  bore  of  which  runs  a 
flexible  wire.  The  outer  tube  is  fixed  at  each  end,  while  the 
power  is  transmitted  by  the  inner  wire.  "It  is  used  to  a  great 
extent  in  speedometers.  A  chain  sometimes  takes  the  place 
of  the  inner  wire  when  the  bends  are  not  too  acute.  In 
the  case  of  pumps,  the  spindle  is  sometimes  driven  by  using 
a  stiff  spiral  spring  as  a  shaft  between  the  pump  spindle  and 
the  shaft  driving  it.  In  this  case,  should  the  pump  itself  jam 
for  any  reason,  the  spring  will  relieve  the  shock. 

Gear  Shaft — A  gear  shaft  carries  gear  wheels  or  pinions 
which  mesh  with  gear  or  pinion  wheels  carried  on  another 
shaft.  In  a  gear-box,  for  instance,  there  are  usually  two 
•gear  shafts,  one  called  the  primary,  being  connected  to  the 
clutch  and  thus  receiving  its  power  from  the  engine,  the  other 
called  the  secondary,  lay  or  countershaft,  being  connected -to 
it  by  gear,  wheels  and  transmitting  the  power  to  the  road 
wheels.  See  Change  Speed  Gear. 

Half-speed  Shaft— See  Camshaft. 

Hollow  Shaft — Many  crankshafts  are  now  made  hollow,  as 
also  are  some  other -shafts,  such  as  rocking  shafts. 

Intermediate  Shaft — A  term  applied  to  any  shaft  which 
transmits  power  from  one  shaft  to  another  either  by  means 
of  belts  or  gears.  The  name  is  generally  used  in  connection 
with  the  secondary  gear  shaft.  (See  Secondary  Shaft.) 

Jack  Shaft — Same  as  Countershaft  or  Cross'  Shaft. 

Lay  Shaft — ^The  same  description  applies  to  Lay  Shaft  as 
to  Intermediate  Shaft.  See  Secondary  Shaft. 


190  MOTORS  AND  MECHANISM 

Motor  Shaft — See  Crankshaft. 

Primary  Shaft — The  shaft  in  the  gear-box  which  takes  its 
power  from  the  engine  and  transmits  it  to  the  secondary 
shaft.  See  Change  Speed  Gear. 

Propeller  Shaft— This  is  the  shaft  which  transmits  the 
power  from  the  gear-box  to  the  back  live  axle.  It  is  pro- 
vided with  universal  joints  at  either  end,  so  that  it  can  adapt 
itself  to  the  varying  angle  between  the  gear-box  and  the  axle 
due  to  the  motion  of  the  springs.  See  Secondary  Shaft  and 
Transmission. 

Reversing  Shaft — The  small  shaft  in  the  gear-box  which 
carries  the  reversing  gear  wheel ;  really  an  intermediate  shaft. 

Secondary  Shaft — The  shaft  in  the  gear-box  which  trans- 
mits the  power  from  the  primary  shaft  to  either  the  propeller 
or  countershaft,  or  back  to  the  primary  shaft.  See  Trans- 
mission. It  is  sometimes  called  a  lay  shaft,  countershaft,  in- 
termediate shaft,  or  gear-shaft. 

Torsion  Shaft — The  shaft  that  runs  through  the  center  of 
a  live  axle  transmitting  the  drive  from  the  differential  gear 
in  the  center  of  the  axle  to  the  road  wheels.  This  shaft  is 
really  the  "live"  part  of  a  live  axle,  the  tube  or  axle  proper 
through  which  it  runs  being  used  solely  to  support  the  springs 
on  which' the  body  rests. 

Transverse  Shaft — A  shaft  set  at  an  angle  to  another  shaft. 
The  countershaft  is  a.  transverse  shaft. 

Two-to-one  Shaft — Same  as  camshaft. 


MOTORS  AND  MECHANISM  191 

• 

CHAPTER  XIII. 
LUBRICATION  AND  LUBRICATORS. 


In  practice  the  lubricant  not  only  serves  to  separate  the 
surfaces  but  also  helps  to  carry  away  the  heat  generated  in 
the  bearings  by  transfering  it  to  the  cool  outer  walls  of  the 
crank  case  from  which  it  is  radiated  to  the  outside  air.  With 
bearings  having  heavy  loads  on  a  limited  area  the  temperature 
is  much  reduced  by  having  a  large  volume  of  oil  continually 
pouring  over  the  shell,  an  amount  greatly  in  excess  of  that 
required  for  the  maintenance  of  the  oil  film. 

In  general,  the  bearings  of  an  automobile  are  supplied  with 
oil  by  three  principal  systems:  (1)  Forced  feed.  (2)  Splash 
system.  (3)  Oil  and  grease  cups.  In  many  cars  all  three  are 
used  in  conjunction  so  as  to  fully  meet  the  varying  conditions 
demanded  by  the  different  types  of  bearings.  The  familiar 
grease  and  oil  cups  are  used  for  the  slowly  moving  parts  that 
are  not  in  continual  use  such  as  the  brake  shafts,  spring  shack- 
les and  steering  knuckles,  or  for  parts  that  only  swing  through 
small  angles  and  have  limited  travel.  The  rapidly  moving 
and  load  carrying  parts  such  as  the  crank-shaft  bearings,  con- 
necting rod  ends,  cam  shafts  and  piston  are  lubricated  by 
either  the  pressure  feed  or  the  splash  system.  As  the  amount 
of  oil  required  by  a  heavy  duty  bearing  depends  both  upon 
its  speed  and  the  load  it  is  usual  to  have  the  supply  controlled 
by  varying  output  of  the  pumps  or  by  varying  the  amount  of 
oil  deposited. 

In  the*  force  feed  system  the  oil  is  forced  into  the  bearings 
directly  by  means  of  a  high  pressure  pump.  This  pump  being 
driven  by  the  motor,  feeds  the  oil  in  direct  proportion  to  the 
motor  speed  but  the  quantity  is  independent  of  the  power 
developed.  Oil  is  fed  a  drop  at  a  time  but  at  such  a  pressure 


192 


MOTORS  AND  MECHANISM 


that  it  is  forced  into  the  innermost  parts  of  the  bearing  surface, 
thus  insuring  minimum  wear  of  the  parts.  There  is  generally 
a  separate  pump  and  oil  lead  to  each  bearing,  the  separate 
pumps  being  mounted  in  a  separate  case  carried  either  on  the 
motor  or  on  the  dash  board. 


FORCE    FEED    LUBRICATING    SYSTEM,    SHOWING    PUMP   AND 
FEED  TUBES. 


The  splash  feed  system,  as  its  name  would  suggest,  supplies 
oil  to  the  bearings  within  the  crank  case  in  the  form  of  a  spray 
which  is  developed  by  the  ends  of  the  connecting  rods  striking 
in  a  puddle  of  oil.  The  oil  spray  is  deposited  on  the  interior 
of  the  cylinder*  and  reaches  the  crank  and  cam  shaft  bearing 
through  collecting  pockets  cast  in  the  crank  case.  The  excess 
oil  which  drips  from  .the  bearings  drops  to  the  oil  surnp  in 
the  bottom  of  the  crank  case  from  which  it  returns  to  the  oil 


MOTORS  AND  MECHANISM 


193 


pump  located  in  the  rear  of  the  crank  case.  Leads  from  the 
pump  return  the  oil  to  the  splash  puddles,  thus  using  the  oil 
over  and  over  again  until  it  is  exhausted.  In  some  cases  the 
oil  from  the  pump  is  first  lead  to  the  bearings  from  which 
it  drops  into  the  splash  pockets,  the  splash  being  depended 
on  only  for  lubricating  the  cylinders.  After  overflowing  from 
the  splash  pockets  the  oil  returns  to  the  pump.  The  oil  pump 


JJASR 

:BQAED 


CONTINENTAL  SPLASH  SYSTEM. 

is  usually  of  the  gear  type  although  in  some  cases,  a  plunger 
pump  is  used  which  is  driven  from  the  cam  shaft.  This  sys- 
tem supplies  a  large  quantity  of  oil  but  is  not  easily  regulated, 
and  is  not  well  adapted  to  the  modern  high  speed  eight  and 
twelve  cylinder  motors. 

With  the  force  feed  system  the  pipes  from  the  pumps  gener- 
ally lead  to  the  main  bearings,  the  connection  rod  ends  being 
supplied  from  the  bearings  by  means  of  longitudinal  holes 
drilled  in  the  crank-shaft.  In  some  systems  the  cylinders  are 
fed  individually  by  separate  pump  leads  while  in  others  the 
drip  from  the  bearings  is  used  in  the  splash  pockets  to  oil  the 
cylinders  so  that  in  the  latter  system  we  have  a  combined 
force  feed  and  splash.  In  a  sort  of  semi-force  feed  system,  the 
oil  for  all  bearings  is  furnished  by  a  single  gear  pump  that 
maintains  a  pressure  of  from  10  to  50  pounds  per  square  inch 
on  the  oil  pipes.  The  gear  pump  is  located  in  the  crank-case 


194 


MOTORS  AND  MECHANISM 


and  delivers  oil  to  the  main  bearings  and  cam  shaft.  The  oil 
drip  from  the  bearings  reaches  the  lower  connecting  rod  bear- 
ings through  holes  drilled  in  the  shaft  and  the  excess  from 
this  point  reaches  the  piston  pin  through  a  tube  running  from 
the  lower  connecting  rod  bearing  to  the  piston  pin.  An  auto- 
match  blow-off  valve  regulates  the  pressure  in  the  system 
and  discharges  the  excess  oil. to  the  cam  shaft  gears  in  front 


^ 


GEAR  PUMP  LUBRICATION. 


of  the  crank  case  from  where  it  returns  to  the  pump.    There 
are  no  splash  cups. 

In  the  splash  feed  system  it  is  usual  to  feed  the  lower  end 
bearings  of  the  connecting  rods  through  holes  in  the  dipping 
end  of  the  rods,  the  force  of  the  impact  on  the  oil  puddle  cre- 
ating enough  pressure  to  drive  the  oil  into  the  bearing.  The 
piston  pin  is  fed  by  the  oil  sprayed  into  the  head  of  the  piston 
or  by  the  oil  scraped  off  of  the  cylinder  walls  as  the  piston 
moves  to  and  fro  in  the  bore.  The  rod  ends  throw  oil  into 
pockets  over  the  main  bearings  from  which  the  oil  flows 
through  drilled  holes  into  the  brasses.  The  shaft  is  not  drilled. 
The  return  oil  from  the  bearings  is  circulated  by  a  gear  or 
plunger  pump.  In  some  motors,  notably  the  Knight,  the  splash 
troughs  are  pivoted  to  the  crank  case  and  connected  with  the 
throttle  in  such  a  way  that  the  trough  rises  when  the  throttle 


MOTORS  ANDf  MECHANISM  195 

is  opened.  By  this  arrangement  the  amount  of  oil  fed  is  pro- 
portional to  the  power  developed  by  the  motor  as  the  rising 
troughs  cause  the  connecting  rods  to  dip  more  deeply  and 
hence  to  throw  more  oil. 

When  plunger  pumps  are  used  they  are  driven  from  the 
cam  shaft  by  an  extra  cam,  the  cam  forcing  the  piston  against 
the  oil  while  the  return  stroke  is  made  by  spring.  These 
pumps  work  well  up  to  1800  revolutions  per  minute  (Crank- 
shaft speed)  but  are  likely  to  jump  strokes  at  anything  higher. 
The  principal  trouble  with  a  plunger  pump  is  that  if  dirt 
accumulates  in  the  valves  the  oil  supply  is  stopped,  but  with 
proper  strainers  this  trouble  is  almost  negligible.  Gear  pumps 
are  the  simplest,  have  no  valves  and  can  be  run  successfully 
at  almost  any  practicable  motor  speed.  The  latter,  however, 
are  not  capable  of  as  high  pressures  as  the  plunger  type  are, 
cannot  exert  the  same  force  on  an  obstruction  in  the  pipes.  Oil 
strainers  must  be  provided  with  all  systems  and  should  be 
regularly  cleaned  from  the  accumulated  grit  and  dirt. 

Lubrication  of  Differential. 

The  differential  housing  should  hold  the  lubricant  in  the 
rear  axle  gears.  Sometimes  a  disagreeable  looking  rear  axle 
is  noticed  where  the  oil  or  grease  oozes  out  through  cracks  or 
leaks  in  the  rear  cover  plate  or  through  the  axle  tubes  on  the 
wheels.  This  is  not  so  common  a  fault  now  as  it  used  to  be 
when  axles  were  not  designed  so  well  to  trap  the  oil  and  keep 
it  where  it  belongs.  However,  an  occasional  careless  driver 
will  let  his  axle  get  in  this  condition  by  not  having  a  proper 
gasket  between  the  differential  housing  cover  plate  and  the 
housing  itself.  It  is  not  much  trouble  to  cut  a  gasket  and  it 
saves  much  in  the  appearance  of  the  car  and  health  of  the 
axle  gears. 

In  some  cases,  a  heavy  transmission  oil  is  recommended  for 
the  axle,  but  in  most  instances  it  is  best  to  use  either  a  semi- 
fluid grease  or  even  a  heavy  grease.  It  is  next  to  impossible 
to  give  any  fixed  rule  for  rear  axle  lubrication.  There  are  so 


196  MOTORS  AND  MECHANISM 

many  designs,  and  where  a  heavy  oil  or  a  grease  will  work 
satisfactorily  in  one  instance,  some  other  form  is  better  in 
another. 

Lubrication  of  Gear  Box. 

Parts  that  are  inclosed  require  attention  less  often  than 
those  that  are  exposed.  The  gearbox  will  hold  its  lubricant 
for  quite  a  long  time,  requiring  attention  every  2,000  to  3,000 
miles  or  such  a  matter.  In  filling  the  gearset,  put  in  a  lubri- 
cant to  a  depth  about  half  the  height  of  the  gearbox.  Have 
it  come  about  even  with  the  center  of  the  main  shaft.  This 
will  completely  submerge  the  countershaft  in  the  average 
gearset.  It  is  important  to  see  that  the  packing  rings  are 
tight  and  prevent  leakage  where  the  shafts  emerge  from  the 
gearcase.  If  there  is  leakage  here,  it  will  act  as  a  collector  of 
dirt  and  dust,  and  the  gears  will  be  robbed  of  their  lubrication. 
It  is  important  in  lubricating  the  gearset  that  the  oil  or  grease 
should  not  be  too  heavy,  for  in  that  case  it  will  stick  to  the 
gears  and  be  thrown  from  them  by  centrifugal  force.  Very 
soon,  they  are  free  of  the  very  lubricant  they  have  been  acting 
upon  and  soon  run  hot.  The  best  lubricant  is  a  heavy  oil  that 
will  run,  or  a  grease  of  such  consistency  that  it  will  flow. 
There  are  many  special  forms  of  gearset  semi-fluid  greases  and 
heavy  oils  on  the  market.  It  is  obviously  wrong,  therefore, 
to  put  any  common  grease  into  a  gearset,  for  it  not  only  acts 
as  above,  but  has  not  the  ability  to  get  into  bearings  like  a  fluid 
material. 

Oiling  Schedule. 

The  majority  of  manufacturers  now  furnish  some  form  of 
oiling  chart  on  which  the  oiling  points,  quality  of  oil  and 
intervals  are  plainly  marked.  Careful  attention  should  be  paid 
to  this  diagram,  and  should  be  committed  to  memory  at  the 
earliest  possible  moment  if  good  car  service  is  to  be  expected. 
Never  neglect  the  smallest  or  most  insignificant  oil  hole  for 
it  is  there  for  a  purpose. 


MOTORS  AND  MECHANISM  197 

The  following  table  gives  general  information  in  regard 
to  lubrication  that  will  be  of  benefit  in  default  of  the  maker's 
chart.  For  this  we  are  indebted  to  "Motor  Age." 

GENERAL  OILING  SCHEDULE. 

Parts  to  be  Lubricated  Daily. 

Joints  on  steering  drag  link.    Grease  or  graphite. 

Clutch  collar  and  thrust  bearing.    Grease  or  graphite. 

Spring  bolts.    Grease  or  graphite. 

Tie  rod  and  king  bolts.    Cylinder  oil. 

Fan  bearing  lubricant.    Cylinder  oil. 

In  most  of  the  cases  mentioned  above  cups  are  provided. 
Besides  those  listed  the  crankcase  should  be  brought  to  level 
and  the  tank  should  be  filled  with  oil. 

Parts  to  Be  Lubricated  Every  300  Miles. 

Steering  gear  case.    Grease  or  graphite. 
All  brake  clevises  or  joints.    Cylinder  oil. 
Steering  post.    Cylinder  oil. 

Hand  and  foot  brake  shafts  and  pedal  bearings.  Cylinder 
oil. 

Commutator  cleaned  and  given  few  drops  of  cylinder  oil. 

Parts  to  Be  Lubricated  Every  500  Miles. 

Spring  leaves.    Cylinder  oil  or  graphite. 

Auxiliary  motor  shaft  couplings.     Graphite  or  good  grease. 

Add  libricant  to  gearset.    Grease  or  gear  oil. 

Drain,  clean  and  refill  crankcase.  Cylinder  oil  or  deflocu- 
lated  graphite. 

One  drop  of  oil  on  magneto  distributor  and  oil  holes  pro- 
vided. Cylinder  oil. 

Motor  timing  gears.   Cylinder  oil,  semi-fluid  oil  or  graphite. 

Parts  to  Be  Lubricated  Every  1,000  Miles. 

Drain,  clean  and  refill  all  transmission  gear  cases.  Same  as 
above. 

Repack  universals.  Grease  or  graphite.  Torsion  tube, 
radius  rods,  etc.  Grease  or  graphite. 


198  MOTORS  AND  MECHANISM 

Clean  and  repack  front  and  rear  wheel  bearings.  Grease  or 
graphite. 

In  the  winter  use  cylinder  oil  for  the  gear  compartments  in- 
stead of  grease  or  graphite. 

There  is  much  misinformation  about  the  caring  for  and 
lubrication  of  a  disk  clutch.  Heavy  oil  often  is  put  into  such 
a  mechanism  with  rather  disastrous  results.  At  the  end  of 
a  reasonable  distance,  say  500  miles,  the  old  oil  in  a  disk 
clutch  should  be  removed.  There  is  usually  a  drain  plug 
fitted  to  the  clutch  housing  and  this  should  be  removed  to  let 
the  oil  out,  after  which  the  clutch  should  be  rinsed  with  kero- 
sene, and  again  allowed  to  drain  completely.  Thus  cleaned, 
a  supply  of  a  light  clutch  oil  should  be  put  in  until  the  level 
is  about  even  with  the  bottom  of  the  clutch  shaft.  This 
allows  the  plates  to  pass  through  a  bath  of  oil,  and  is  the 
desirable  condition. 

-Drip  Feed  Adjustment. 

A  little  item  of  great  importance  which  is  often  overlooked 
has  relation  to  the  adjustment  of  drip  lubricators.  The  prac^- 
tice  is  too  common  of  leaving  these  appliances  just  as  received 
from  the  makers,  with  the  result  that  the  frequency  of  the 
dripping  varies  in  accordance  with  the  viscosity  of  the  oil 
used.  A  lubricator  may  be  set  to  supply  accurately  a  sufficient 
and  not  excessive  quantity  of  one  particular  kind  of  oil,  but 
when  upon  a  tour  some  different  brand  of  oil  may  be  pur- 
chased which  will  not  drip  through  the  orifices  of  the  lubri- 
cators with  anything  like  the  freedom  of  the  oil  for  which 
the  lubricators  have  been  adjusted,  with  the  result  that  the 
engine  receives  an  inadequate  supply;  or  an  oil  of  a  much 
lighter  body  may  be  purchased  which  will  drip  through  so 
rapidly  as  to  smother  the  sparking  plugs  and  valves. 

On  Lubricating  Oils. 

In  a  number  of  motors,  although  the  compression  is  good, 
power  is  not  developed  in  accordance  with  the  size  of  the 
cylinders,  and  there  appears  to  be  a  decided  tendency  to 


MOTORS  AND  MECHANISM  199 

overheat  in  the  engine.  This  is  often  due  to  using  a  lubricat- 
ing oil  that  is'  not  suitable  for  the  type  of  engine,  as  it  is  found 
that  an  oil  which  gives  good  results  with  one  type  is  worth- 
less with  another.  An  oil  may  appear  thick,  and  yet  under 
the  heat  and  working  conditions  may  thin  out  to  such  an 
extent  as  altogether  to  lose  its  lubricating  quality.  If  this  is 
experienced  with  water-cooled  motors,  a  good  brand  of  oil 
usually  employed  for  air-cooled  motors  should  be  tried.  The 
results  will  be  found  to  give  satisfaction  in  most  cases. 

Heavier  Lubricating  Oil  for  Summer. 

Each  summer  complaints  are  heard  as  to  overheating  of 
engines.  In  a  number  of  cases  this  is  no  doubt  largely  due 
to  the  employment  of  the  wrong  kind  of  lubricating  oil  for 
summer  use.  For  water-cooled  motors  it  is  not  a  bad  plan  in 
such  cases  to  use  oil  recommended  for  air-cooled  motors,  as 
this  oil  is  much  thinner  in  summer  when  in  use,  and  conse- 
quently becomes  about  the  right  consistency  for  the  proper 
amount  of  feed  during  the  summer  months.  Of  course,  as 
the  weather  becomes  colder  the  usual  brand  of  lubricating  oil 
should  again  be  used. 

Over-lubrication. 

When  a  thick  cloud  of  blue  pungent  smoke  is  ejected  from 
the  muffler  it  is  a  sign  that  there  is  too  much  oil  in  the  engine. 
While  it  must  be  admitted  that  this  is  good  for  many  engines, 
especially  when  new,  it  must  not  be  forgotten  that  such  an 
emission  is  highly  objectionable  to  everybody  but  those  in  the 
car.  A  simple  and  effective  method  of  correcting  this  trouble 
is  to  open  the  compression  cocks,  when  such  are  fitted,  one 
by  one.  This  quickly  clears  the  cylinder,  and  with  a  surpris- 
ingly small  amount  of  attendant  mess  when  there  is  a  clear 
way  for  the  ejected  oil.  With  a  single-cylinder  engine  it  is, 
of  course,  necessary  to  give  the  piston  the  necessary  move- 
ment by  hand.  It  is  a  somewhat  extraordinary  thing;  but  many 
engines  will  run  with  quite  an  overdose  of  oil  without  trouble, 
while  others  have  a  very  decided  objection  to  a  too  liberal 
supply  of  lubricant.  For  instance,  a  Daimler  car  requires  but 


200  MOTORS  AND  MECHANISM 

a  small  amount  of  oil,  while,  on  the  other  hand,  a  Mercedes 
simply  gloats  on  a  full  charge.  Many  makers  adopt  the  ex- 
pedient of  fitting  an  overflow  pipe  in  the  bottom  of  the  crank 
chamber  to  prevent  the  engine  getting  more  than  is  good  for  it. 

Take  Nothing  for   Granted. 

Nothing  should  be  taken  for  granted  in  the  lubrication  of  an 
automobile.  Everything  should  be  done  to  make  the  work 
of  lubrication  as  easy  as  possible  by  having  every  convenience 
at  hand.  The  plugs  and  cocks  designed  for  the  drawing  off 
of  the  spent  oil  from  crank  cases  should  be  looked  after  care- 
fully to  see  that  they  cannot  work  loose  while  running.  If 
an  undue  amount  of  oil  drips  from  any  particular  point  of  the 
vehicle,  it  may  indicate  either  that  the  supply  is  excessive, 
that  means  for  retaining  it  are  not  proper  or  that  the  oil 
is  "too  thin.  Thick  oil,  on  the  whole,  gives  little  trouble  from 
working  out  of  bearings,  especially  when  everything  is  worn. 
The  cleaning  down  of  a  car  is  a  duty  which  no  one  having 
the  instincts  of  a  mechanic  will  shirk,  as  the  dust  which  an 
excess  of  oil  on  the  outside  surfaces  of  the  wearing  parts  is 
constantly  collecting  may  prove  very  injurious  to  the  mech- 
anism. 

Preserving  Oil  Holes  from  Dirt. 

Most  users  of  cars  are  very  neglectful  in  their  oiling  of 
short  shafts  such  as  brakeshafts,  clutchshafts,  and  the  like. 
They  simply  think  that  these  parts  can  be  left  to  take  care 
of  themselves,  whereas  they  should  be  lubricated  as  regularly, 
although  not  so  frequently,  as  the  gear-box  bearing  or  road- 
wheel  bearings.  As  a  number  of  brake  spindles  are  carried  on 
cast  bosses  which  readily  lend  themselves  to  the  fitting  of 
clip  rings  over  the  oil  holes,  these  clip  rings,  such  as  are 
usually  fitted  to  the  hub  of  a  bicycle  wheel,  should  be  fitted 
over  the  o:.l  holes,  and  thus  no  dirt  or  wet  can  be  allowed 
to  get  in  the  shaft  bearings.  The  brakes  work  much  more 
sweetly  and  also  clutchshafts  have  less  friction,  so  that  less 
effort  is  required  to  depress  the  clutch  or  apply  the  foot  brake. 
Cases  have  been  known  of  a  rear  brakeshaft  which  was  ab.- 


'MOTORS  AND  MECHANISM  201 

solutely  rusted  solid  in  its  place,  and  could  not  be  moved  at 
all ;  thus  the  rear  brakes  were  rendered  quite  useless  through 
simple  neglect  of  fitting  clips  and  oiling,  the  parts  regularly. 

Kerosene  Pump  Lubricator. 

If  your  car  is  unprovided  with  means  by  which  kerosene 
can  be  injected  into  the  cylinder,  and  the  latter  is  not  fitted 
with  a  compression  cock,  have  a  kerosene  pump  lubricator 
fitted  to  the  dashboard  with  a  delivery  pipe,  or,  in  the  case  of 
multiple  cylinders,  forked  delivery'  pipes  to  the  lubricating 
pipes,  as  close  to  the  entrance  of  the  latter  to  the  cylinder 
as  possible.  The  cylinder  oil  pipes  must  be  provided  with 
cocks  just  above  the  junction  of  the  kerosene  pipes^  so  that  by 
turning  off  these  before  you  do  your  kerosene  pumping  on 
coming  in  from  your  run,  the  latter  oil  is  not  forced  back,  as 
it  may  be,  into  the  cylinder  oil  tank.  Above  all,  do  not  forget 
to  turn  these  added  lubricating  oil  cocks  on  directly  after  you 
have  flushed  with  kerosene.-  Forgetfulness  in  this  particular 
may  mean  seizing,  with  all  its  horrors. 

Cleaning  Grease  Pipes. 

It  is  not  often  that  grease  pipes  require  clearing  out,  for 
which  we  ought  to  be  duly  thankful,  for  if  the  pipe  be  of  any 
length,  or  contain  complicated  turns,  then  there  are  great  pos- 
sibilities of  trouble.  The  best  way  to  start  is  to  pass  a  piece 
of  stiff  wire  through  the  grease  in  the  pipe,  if  possible,  and 
if  this  may  be  done,  then  lay  the  pipe  in  a  tray  and  keep  it 
covered  with  gasolene.  This  treatment  will  soften  the  grease, 
and  clear  some  of  it  out,  so  that  the  pipe  may  be  charged  with 
successive  doses  of  gasolene  and  cleaned  like  a  bottle.  If 
one  is  lucky  enough  to  have  access  to  a  steam  boiler,  then 
the  pipe  may  be  cleared  by  attaching  it  to  the  blow-off  cock 
on  the  water  gauge.  It  needs  caution,  however,  when  follow- 
ing this  method  of  procedure,  or  scalded  hands  or  worse  may 
follow.  The  safer  plan  is  most  certainly  that  first  outlined, 
but  the  latter  is  much  quicker  and  cleaner. 

For  cleaning  out  the  small  pipes,  a  very  good  method  is  to 
use  a  pump  made  out  of  a  bicycle  tire  inflater.  this  being  pro- 


202  MOTORS  AND  MECHANISM 

vided  with  a  brass  nozzle,  with  a  coned  end,  so  that  it  can 
be  put  into  the  end  of  the  pipe  and  the  contents  vigorously 
discharged  through  it,  thus  dissolving  and  clearing  away  any 
congealed  oil  or  other  obstructive  matter. 

Grease  Injection. 

Some  cars  require  grease  to  be  injected  into  most  inacces- 
sible places.  We  have  in  mind  a  machine  which  takes  grease 
for  its  differential  and  for  its  two-to-one  gear  through  holes 
of  one  inch  in  diameter,  these  holes  being  covered  with  screw 
plugs.  Now,  to  push  sufficient  grease  through  these  small 
orifices  is  a  dirty  and  almost  interminable  task.  The  owner 
overcame  the  difficulty  by  pressing  into  service  an  old  grease 
lubricator  of  the  screw-down  type.  This  lubricator  was  a 
gunmetal  pot  about  four  inches  wide  and  as  many  deep.  In 
the  screw  lid  there  is  a  piston  with  a  screw  handle,  so  that 
when  the  pot  is  filled  with  grease  it  can  be  forced  out  by 
turning  the  handle  round.  At  the  bottom  of  the  pot  there  is 
a  piece  of  copper  tube  eight  or  ten  inches  long,  so  there  is 
nothing  easier  than  to  insert  this  tube  into  the  holes  and 
then  to  screw  down  the  lubricator,  thus  emptying  its  contents 
into  the  gear-box. 

It  may  be  interesting  to  add  that  we  have  found  the  easiest 
way  to  handle  grease,  when  one  is  filling  the  pot  or  putting 
a  considerable  quantity  into  the  change  speed  gear-box,  is  to 
use  a  small  garden  trowel  kept  especially  for  the  purpose,  and 
entirely  free  from  grit.  This  is  a  very  clean  and  quick  method 
of  dealing  with  8  or  10  Ibs.  of  grease,  and  infinitely  more 
satisfactory  than  the  ordinary  way  of  picking  up  small  pieces 
on  the  end  of  a  flat  piece  of  wood,  or  digging  one's  hands  into 
the  mess  and  throwing  it  handful  by  handful  into  the  box. 

Care  of  Grease  Lubricators. 

Pressure  should  always  be  kept  on  screw-down  feed  lubri- 
cators serving  grease  on  to  bearings.  Owners  should  get  into 
the  habit  of  giving  the  caps  of  the  lubricators  an  eighth, 
quarter,  or  half-turn  frequently.  Overmuch  is  vastly  better 
than  too  little  lubrication  in  such  bearings  as  are  so  served. 


'MOTORS  AND  MECHANISM  203 

When  taking  over  a  new  car,  make  certain  that  the  grease 
lubricator  has  been  filled  and  screwed  down,  and  filled  and 
screwed  down  again  and  again,  until  the  grease  is  really  serv- 
ing on  to  the  bearing,  for  in  some  cars  the  pipe  leads  from 
these  lubricators  are  so  long  that  several  charges  of  the  lubri- 
cator are  necessary  to  fill  the  pipe  before  the  grease  really 
reaches  the  bearing.  New  bearings  have  seized  or  stuck  be- 
fore now  for  lack  of  this  precaution. 

It  is  often  noticeable  that  the  ordinary  screw-down  lubri- 
cator is  very  hard  to  manipulate.  This  is  due  to  the  feed- 
hole  at  the  bottom  of  the  lubricator  being  too  small  or  to 
the  lead  pipe  communicating  with  the  bearings  having  too 
small  a  bore.  There  is  no  reason  why  screw-down  lubricators 
should  be  made  so  difficult  to  operate;  this  matter  really  de- 
serves more  attention  from  the  manufacturers  and  those  who 
have  to  use  them.  The  screw  portion  should  be  capable  of 
being  easily  twisted  round  by  means  of  the  thumb  and  fore- 
finger, and  not  have  to  be  forced  down  with  the  hardest  stress 
which  can  be  put  on  with  the  hand  or  with  a  spanner. 

Commutator  Troubles. 

Car  owners  whose  high  tension  ignition  systems  include  a. 
rolling  contact  maker  of  the  Lacoste  type  cannot  be  too  careful 
about  the  lubrication  of  the  commutator.  When  cars  so 
fitted  are  first  received  from  the  makers,  the  interior  of  the 
commutator  case  will  or  should  be  found  packed  with  a  some- 
what thin  grease,  with  which  the  action  of  contact-making  as 
the  roller  on  the  little  arm  passes  over  the  brass  or  steel 
terminals  appears  to  be  as  perfect  as  possible.  After  four  or 
five  hundred  miles,  the  engine  may  be  found  to  fire  imperfectly 
on  one  or  more  cylinders,  particularly  when  accelerated,  and 
the.n  such  failures  will  frequently  find  their  cure  by  the  care- 
ful washing  out  of  the  commutator  with  gasolene,  and,  when 
the  latter  has  dried  off,  the  application  of  fresh  grease.  Care, 
however,  should  be  taken  as  to  the  grease  applied,  for  there  are 
several  very  stiff  kinds  sold  which,  though  good  enough  for 
bearings,  are  by  no  means  suitable  for  commutator  lubrication. 


204  MOTOR'S  AND  MECHANISM 

An  Oil  Force  Pump. 

It  is  a  great  convenience  to  have  a  force  pump  for  oil  on  the 
car— some  7  or  8  inches  long,  and  really  well  constructed. 
With  this  the  very  thickest  of  oil  can  be  picked  up  and  in- 
jected into  almost  any  part  of  the  car.  It  is  most  useful  for 
lubricating  many  places,  and  comes  in  handily  in  a  number  of 
ways'.  For  instance,  supposing  it  is  found  when  on  the  road 
that  the  differential  should  be  lubricated.  The  arrangement 
for  this  in  some  cars  is  rather  crude,  and  the  only  provision 
for  lubrication  is  to  undo  a  screw  plug  at  the  top  or  the  side 
of  the  differential  casing — we  are  speaking  of  gear-driven  cars 
— and  it  is  a  long  job  to  empty  an  oil  can  into  the  case,  but 
three  or  four  syringefuls  of  oil  can  be  injected  in  a  very  short 
time  indeed.  The  pump  can  also  be  used  for  kerosene  for 
cleaning  purposes,  though,  of  course,  after  being  so  used  it 
should  be  thoroughly  cleaned  with  stale  gasolene  before  being 
used  again  for  lubricating  oil.  The  pump  can  also  be  used 
for  introducing  grease  into  awkward  places.  The  quickest  way 
to  do  this  is  to  put  the  grease  in  a  breakfast  cup  or  small 
pot,  and  place  the  vessel  in  a  pan  of  boiling  water.  The 
grease  will  then  be  taken  by  the  pump  as  though  it  were  thick 
oil.  To  prevent  the  fingers,  being  burned  with  the  hot  pump, 
a  thick  rag  should  be  used  as  a  protection,  especially  if  the 
pump  has,  as  it  should  have,  a  couple  of  hooked  finger  plates 
at  the  end  of  the  barrel,  as  well  as  a  finger  ring  on  the  plunger. 

Lubricators  for  Spring  Shackles. 

Many  cars,  especially  high  priced  ones,  are  fitted  with 
lubricators  to  each  of  the  bearings  on  the  spring  shackles. 
Lower  priced  cars  have  merely  oil  holes,  and  the  user  is  ex- 
pected to  fill  these  from  time  to  time.  In  cheaper  cars  these 
oil  holes  are  omitted,  but  where  possible  they  should  be  made, 
as  wear  sets  up  in  the  joints  of  these  shackles  and  has  a  ten- 
dency to  cause  rattling  after  the  car  has  been  on  the  road  for 
a  few  months.  Where  the  oil  holes  are  provided,  and  it  is  de- 
sired to  close  them  in  some  way,  this  can  be  done  quite  easily 
by  the  user  himself,  by  means  of  the  covers  such  as  are  used 


MOTORS  AND  MECHANISM  205 

on  bicycles.  The  types  we  refer,  to  more  particularly  are  the 
spring  bands  which  are  used  on  bicycle  pedals.  These  can  be 
obtained  of  different  sizes,  and  can  be  sprung  round  the  shackle 
bearings  effectually  to  prevent  dust  getting  in,  and  yet  allow 
easy  access  to  the  holes  when  necessary. 

Good  Mufflers  and  Lubrication. 

Where  in  some  cars  the  muffler  has  been  carefully  studied 
to  avoid  back  pressure,  this  may  have  been  done  so  effectually, 
that  a  very  feeble  pressure  passes  to  the  lubricator,  and  some- 
times on  a  cold  day  no  feed  therefrom  can  be  obtained.  When 
this  is  so,  there  are  two  courses  open :  The  first  is  to  force  some 
oil  through  the  pipes,  and  that  can  be  done  by  getting  some- 
one to  put  the  sole  of  his  shoe  over  the  exhaust  outlet,  when 
the  throttle  can  be  opened;  the  engine  will  not  race,  as  it 
will  be  slowed  by  choking  the  exhaust  outlet.  This  will 
cause  the  oil  to  pour  through  the  lubricator  sight  drip  jets  in 
fine  style.  The  second  procedure  is  slightly  to  warm  the  oil. 
This  can  be  done  by  arranging  a  leak  somewhere,  so  that  the 
exhaust  coming  into  the  lubricator  can  pass  right  through  for 
a  time,  and  so  gradually  get  some  warm  air  through.  If,  how- 
ever, the  lubricator  used  to  feed  well,  but  becomes  worse  as 
time  goes  on,  there  is  another  thing  to  be  looked  for,  and  that 
is,  that  the  oil,  for  some  unexplained  reason,  has  found  its 
way  into  the  oil  pipe  that  connects  the  lubricator  to  the  large 
exhaust  pipe,  and  has  become  crusted  up.  This  has  been  found 
the  case  with  many  cars  under  repair,  and  it  is  a  thing  one 
might  look  for  indefinitely  without  finding  it  out. 

The  Smell  from  Cars. 

There  is  no  need  for  us  to  dwell  upon  the  evils  of  over- 
lubrication  so  far  as  smoke  and  smell  are  concerned,  but 
there  are  some  cars  which,  whether  they  be  over-lubricated  or 
not,  always  smell  more  or  less,  and  it  will  be  found  that 
this  smell  is  different  from  the  ordinary  odor  of  burned  lubri- 
cating oil.  In  most  cases  it  is  due  to  oil  or  grease  leaking 
from  the  gear-box  and  thrown  by  the  shaft  on  to  the  hot  ex- 
haust pipe.  At  this  point  the  pipe  may  not  be  hot  enough  to 


s; 


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i|l£^'sl§H  0^12,80^ 

isffipfibi!! 


Ert*''hOOlH&<')^ 

ifaUiMijIUi 


MOTORS  AND  MECHANISM  207 

really  burn  the  oil  up  immediately,  but  it  gradually  fries  it, 
arid  makes  a  most  unpleasant  odor  in  so  doing. 

The  remedy  is  a  simple  and  obvious  one.  As  a  rule,  the 
leakage,  if  round  the  primary  shaft  of  the  gear-box  bearing, 
cannot  be  stopped,  and  the  thing  to  do  is  to  protect  the  ex- 
haust pipe  from  the  splashes.  This  can  always  be  done  by 
fitting  a  thin  sheet  iron  shield  an  inch  or  two  from  the  ex- 
haust pipe  and  between  it  and  the  line  of  the  oil  splashes. 

When  driving  slowly,  too,  it  has  been  found  that  in  many 
cases  cars  which  have  the  muffler  in  front  of  the  back  axle 
are  much  more  likely  to  emit  unpleasant  odors,  of  which  the 
occupants  of  the  car  are  unpleasantly  conscious,  than  if  the 
muffler  is  fitted  further  back.  The  muffler  at  the  back  with  the 
final  exhaust  directed  at  a  slight  downward  angle  is  less 
likely  to  cause  inconvenience.  Of  course,  it  will  be  under- 
stood that  the  angle  of  the  exhaust  as  it  issues  to  the. air  will 
be  only  slightly  downward.  It  will  never  beat  upon  the  road, 
and  if  a  line  were  taken  from  it  to' the  road  it  would  not  touch 
the  ground  till  it  was  at  least  ten  or  twelve  feet  behind  the 
car,  so  that  it  has  no  disturbing  effect  upon  the  dust;  in  fact, 
if  anything,  it  should  tend  to  reduce  dust  raising. 


LUBRICATORS. 

Lubricators — These  may  be  classed  under  two  heads- 
gravity  feed  and  forced  feed. 

Gravity  Feed. 

In  gravity-feed  lubricators  the  lubricant  is  placed  in  a 
chamber  higher  than  the  point  at  which  it  is  to  be  applied, 
and  by  its  own  weight  travels  down  to  the  oil  squeezed  from 
between  the  surfaces  to  be  lubricated.  Even  where  a  simple 


208  MOTORS  AND  MECHANISM 

oil  cup  is  placed  in  a  bearing  it  acts  by  gravity,  the  oil  drop- 
ping down  to  replace  that  used  up. 

It  is  generally  considered  necessary  to  provide  in  this  sys- 
tem of  lubrication  for  some  form  of  sight  feed,  so  that  ocular 
demonstrations  may  be  obtained  as  to  whether  the  oil  is  flow- 
ing or  not. 

Sight  Feed  or  Drip  Lubricators — Generally  placed  on  the 
dashboard  of  the  car,  and  immediately  under  the  eye  of  the 
driver.  The  oil  drops  from  the  oil  chamber  through  a  needle 
valve,  which  can  be  regulated  to  allow  it  to  pass  the  oil  in 
the  form  of  drops  through  a  glass  tube  where  the  speed  of  the 
dropping  can  be  easily  seen,  and  the  needle  valve  can  be 
easily  adjusted  to  cause  the  requisite  number  to  fall  in  a 
given  time.  A  number  of  these  drips  or  sight  feeds  can  be 
arranged  from  one  oil  reservoir,  each  one  communicating  by 
a  pipe  to  the  particular  part  of  the  car  to  be  lubricated. 

Forced  Feed  Lubricators. 

In  forced  feed  lubricators  the  oil  is  forced  by  a  rotating  or 
reciprocating  pump,  via  small  tubes,  to  each  journal  or  bear- 
ing to  be  lubricated.  It  flows  in  a  constant  stream  as  long  as 
the  engine  continues  to  run  and  to  drive  the  pump.  The  oil 
flows  over  and  around  or  through  the  bearing  or  sliding  sur- 
faces, and  is  collected  in  a  drain  chamber  somewhere  below 
the  bearings,  generally  in  a  recess  formed  in  the  base  of  the 
crank  case  or  gear-box  for  this  purpose.  It  is  from  this  cham- 
ber that  the  pump  draws  its  supply,  so  that  there  is  a  con- 
stant circulation  of  the  oil  from  the  oil  pump  to  each  bearing 
and  back  to  the  oil  pump  again. 

The  feed  of  the  oil  from  the  tank  may  be  either  by  gravity, 
as  we  have  seen,  or  forced.  In  the  latter  case  the  tank  may  be 
placed  in  any  convenient  position  on  the  car,  and  the  oil  is 
forced  from  it  by  air  pressure  in  the  tank  itself.  This  air  pres- 
sure may  be  obtained  by  means  of  a  small  hand  pump,  and  a 
pressure  gauge  on  the  dashboard  indicates  to  the  driver  if 
the  requisite  pressure  is  in  the  tank  to  keep  the  oil  properly 
fed  to  the  different  bearings. 


MOTORS  'AND  MECHANISM  209 

In  another  system  the  pressure  of  the  exhaust  gas  is  used 
to  force  the  oil  through  the  oil  pipes  to  the  various  bearings. 
Part  of  the  exhaust  gases  are  passed  through  a  non-return 
valve  and  filter  into  the  oil  reservoir,  maintaining  such  pres- 
sure as  may  be  required,  a  pressure  relief  valve  being  some- 
times fitted  to  prevent  the  pressure  in  the  tank  rising  above 
a  predetermined  amount.  This  system  has  the  advantage  of 
slightly  raising  the  temperature  of  the  oil,  and  this  allows  an 
oil  of  greater  viscosity  to  be  used. 

In  all  cases  the  oil  passes  through  sight  feed  lubricators  on 
the  dashboard,  so  that  the  driver  may  be  assured  that  this  im- 
portant operation  is  going  on  properly.  See  Internal  Combus- 
tion Engine. 

Forced  feed  lubrication  is  also  used  in  some  cases  on*  bear- 
ings which  are  fed  with  heavy  grease.  In  a  lubricator  of  this 
type  the  thick  grease  is  contained  in  a  cup  which  has  in  its 
top  a  plunger  pressed  down  on  the  grease  by  a  helical  spring. 
As  the  grease  is  used  up  in  the  bearing  and  flows  away,  the 
'pring  plunger  forces  the  thick  grease  down  to  take  its  place. 

Pump  Lubricators — The  pump  lubricator  is  almost  always 
of  the  screw-down  grease  cup  type. 

Ring  Lubricators. 

These  are  now  often  used,  especially  in  the  bearings  of  en- 
gine crank  shafts  and  the  shafts  of  change  speed  gears.  In 
this  type  the  center  part  of  the  bearing  is  cut  away,  forming 
an  annular  chamber  around  the  journal  or  shaft.  In  this 
chamber  and  around  the  shaft  hangs  a  loose  ring  of  larger 
dimensions  than  the  shaft.  The  bottom  part  of  this  ring  dips 
in  an  oil  bath  in  the  bottom  of  the  annular  chamber,  and  as 
the  shaft  revolves  it  revolves  the  ring  hanging  upon  it,  which 
carries  around  with  it  the  oil  from  the  oil  bath,  and  deposits  it 
over  the  shaft,  from  which  it  runs  to  the  bearing  parts  at  each 
side  of  the  annular  chamber. 

Splash  Lubrication. 

This  is  used  for  lubricating  the  crank  pins,  gudgeon  pins, 
and  pistons  of  engines  either  independently  or  in  connection 


210  MOTORS  AND  MECHANISM 

with  drip  lubricators  or  force  pumps.  In  this  system  the 
crank  case  is  filled  with  lubricant  to  such  a  height  as  will  al- 
low of  the  cranks  dipping  into  it  at  the  bottom  of  each  down- 
ward stroke.  The  oil  is  then  splashed  upward,  and  effectively 
lubricates  the  whole  of  the  inside  wearing  parts  of  the  en- 
gine. The  oil,  which  is  very  thick  before  it  is  put  into  the 
crank  case,  but  becomes  thinner  afterward  on  account  of  the 
rise  in  temperature  which  it  there  encounters,  is  forced  into 
the  crank  case  by  means  of  a  hand  force-pump,  generally  sit- 
uated on  the  dashboard,  and  provided  with  a  cock,  which  com- 
municates with  the  crank  chamber,  one  or  two  strokes  of  the 
piston  of  this  pump  supplying  oil  for  a  determined  number  of 
miles  running. 

Graphite  Lubrication. 

A  mixture  of  graphite  or  plumbago  and  grease  is  often  used 
on  the  chains,  chain  wheels,  and  chain  sprockets  of  chain- 
driven  cars,  especially  in  cases  where  such  chains  are  not  pro- 
tected by  efficient  chain  cases. 


MOTORS  AND  MECHANISM  211 

CHAPTER  XIV. 
PUMPS. 

Pumps  are  used  in  both  gasolene  and  steam  cars.  The  pumps 
fitted  to  the  latter  are  described  further  on  in  this  article  un- 
der "Steam  Engine  Pumps."  The  following  types  have  been 
adopted  in  gasolene  cars: 

Centrifugal  Pump — In  this  pump  a  number  of  curved  blades 
fixed  to  a  center  boss  are  rotated  in  a  closed  chamber.     The 


FIG      I — CENTRJFUGAL   PUMP. 

E  E  E,  Pump  casing.  V  V  V  V,  Fan  blades  or  vanes. 

C  C  C,  Suction  area  at  center  of  fan  D,  Delivery  pipe. 

B,  Fan.  A,  Driving  shall. 

water  is  caught  by  the  blades  and  forced  upward  to  the  dis- 
charge pipe. 

The  illustration  shows  a  vertical  section  of  a  centrifugal 
pump.  EE  is  the  casing  having  the  tangential  delivery  pipe 
at  D.  B  is  the  fan  of  the  pump  having  the  curved  vanes  V, 
V,  V,  V  cast  with  it.  This  fan  is  made  with  sides  and  is 
hollow  in  the  center.  It  is  mounted  on  a  spindle  A,  which  is 


212  MOTORS  AND  MECHANISM 

rotated  at  a  high  rate  of  speed  from  the  engine  either  by 
friction  disk  or  gear  wheels.  The  water  enters  the  center  C 
of  the  fan,  and  is  ejected  from  the  periphery  by  centrifugal 
force  along  the  pipe  D,  whence  it  is  conducted  to  the  water 
jacket  of  the  motor.  Pumps  of  this  description  are  reliable, 
and  are  widely  used  for  circulation  purposes. 

The  arrangement  of  the  pump  and  the  method  of  driving 
it  are  of  considerable  importance.  The  earlier  types  of  cen- 
trifugal pumps  were  arranged  to  be  swiveled  on  a  hinge  or 
joint ;  they  had  a  friction  wheel  with  a  leather  periphery,  and 
this  friction  wheel  was  kept  in  engagement  with  the  rim  of 
the  flywheel"  by  means  of  a  spring.  So  long  as  oil,  wet,  and 
dirt  could  be  kept  away  from  the  flywheel  this  pump  acted 
fairly  well,  but  the  leather  wore  and  the  spring  lost  its 
strength,  and  often  the  pump  slipped  and  flats  were  worn  on 
the  leather,  with  the  result  that  sometimes  the  pump  would 
remain  out  of  operation  for  a  considerable  time.  Modern 
pumps  are  generally  geared  direct  to  the  engine,  and,  to  pre- 
vent trouble  through  their  freezing,  or  anything  jamming  the 
pump,  they  are  fitted  with  some  form  of  joint  which  will 
easily  give  way  so  as  to  prevent  injury  to  the  engine,  or  to 
the  vital  parts  of  the  pump.  They  are  also  generally  arranged 
so  as  to  be  easily  detachable  for  the  purposes  of  examination 
and  adjustment. 

In  a  typical  modern  method  of  attaching  the  pump  to  the 
engine,  an  extension  of  the  crank-case  forms  a  bracket  of  semi- 
circular section,  and  to  this  bracket  the  pump  is  attached 
by  means  of  a  second  bracket,  also  of  semi-circular  section. 
When  bolted  together  the  two  form  a  kind  of  half  case,  in 
which  will  collect  any  water  or  oil  which  might  leak  through. 
The  pump  is  connected  to  a  camshaft  by  means  of  an  Old- 
ham  joint,  a  form  of  the  universal  joint.  A  big  hexagon  nut 
secures  the  packing  in  the  stuffing-box.  At  the  top  of  the 
pump  is  the  screw-down  grease  lubricator,  and  at  the  bottom 
is  a  draincock,  by  means  of  which  the  water  can  be  drawn 
off  when  leaving  the  car  in  cold  weather.  This  arrangement 
of  the  pump  necessitates  only  one  water-tight  joint,  and  it 


MOTORS  AND  MECHANISM  213 

/ 

has  this  advantage  also  that  the  front  plate  which  carries  the 
inlet  can  be  easily  removed  by  undoing  the  hexagon  screws 
that  hold  its  flange  in  position. 

Propeller  Pump — A  type  of  pump  which  has  lately  come 
into  considerable  vogue  is  the  combined  centrifugal  and  pro- 
peller pump.  In  these  the  vanes  of  the  pump  are  so  arranged 
that  they  not  only  throw  the  water  out  by  centrifugal  action, 
but  act  also  as  a  kind  of  screw,  much  in  the  same  way  as  a 
screw  propeller,  and  push  the  water  along  from  the  inlet  to 
the  outlet  of  the  pump. 

A  good  example  of  this  type  of  pump  has  the  pump  casing, 
with  the  water  inlet  concentric  with  it.  The  water  outlet  is 
at  one  side  of  the  pump  chamber.  A  cover  which  fits  on  the 
flat  face  of  the  pump  chamber  carries  a  bearing  in  which  is 
mounted  the  propeller  shaft.  On  this  is  the  propeller  blade, 
which  approximately  fits  the  inside  surface  of  the  pump  cham- 
ber. The  shape  of  the  propeller  blade  is  such  that  water  en- 
tering at  the  inlet  is  forced  along  by  the  wings  of  the  pro- 
peller both  forward  and  outward,  and  flows  through  the  out- 
let, partly  by  centrifugal  action,  and  partly  by  the  pushing 
action  of  the  propeller  blades.  The  advantage  of  both  these 
types  of  pumps — that  is,  both  the  propeller  and  the  centrif- 
ugal— is  that  should  anything  become  jammed  or  the  con- 
nection between  the  pump  and  its  driving  power  fail,  the 
water  may  flow  through  past  the  blades  by  thermb-syphonic 
action,  thus  to  a  great  extent  preventing  overheating  from 
pump  failures. 

Rotary  or  Gear  Pump — Among  the  direct-acting  pumps, 
that  is  to  say,  pumps  which  actually  drive  the  water  in  known 
quantities  for  each  revolution,  we  have  one  or  two  of  the  ro- 
tary type.  These  are  generally  known  as  "Gear  Pumps," 
because  they  consist  of  two  rotated  members  gearing  with 
one  another  always,  exactly  as  two  pinions  mesh  together. 
These  rotate  in  a  closed  chamber  which  exactly  fits  their 
sides,  and  whose  outside  walls  are  arranged  close  to  their 
periphery,  so  that  there  is  practically  no  space  for  the  water 
to  pass  round  them.  They  are  very  positive  in  their  action, 


214 


MOTORS  AND  M  EC  PI  AN  ISM 


and  can  be  driven  at  high  speeds,  but  they  suffer  from  the 
disadvantage  that  should  their  rotation  fail  from  any  cause, 
the  water  circulation  is  effectually  stopped,  and  rapid  heating 
of  the  cylinder  walls  naturally  takes  place.  Generally  the 
gears  of  these  pumps  are  simply  two  solid  gear  wheels  rotat- 
ing in  the  pump  chamber,  there  being  no  packing  of  any 
kind  between  the  edge  of  the  teeth  and  the  walls. 


THE   ALBANY   GEAR   PUMP. 

In  Fig1.  2  a  form  of  this  pump  is  shown  which  is  typical  of 
its  class,  with  the  exception  that  in  this  particular  pump  an 
ingenious  method  has  been  adopted  for  making  what  might 
be  called  a  water-tight  joint  between  the  teeth  of  the  pump 
and  the  inner  side  of  the  chamber  walls.  It  will  be  seen  that 
each  vane  or  tooth  has  a  narrow  slot  cut  down  the  center 
radially,  with  a  rather  wider  opening  at  its  mouth.  When 
the  pump  is  rotated  at  a  high  speed  it  is  claimed  that  the 
water  which  lies  in  this  slot  is  forcibly  thrown  out  by  the 
centrifugal  action,  and  forms  a  water  joint  between  the  pump 
vanes  and  the  chamber  walls. 

Steam  Engine  Pumps. 

Steam  Pump — This  type  of  pump  is  now  much  used  for 
steam  motor  cars,  both  for  supplying  water  to  the  boiler  and 
for  keeping  a  constant  pressure  of  air  in  the  spirit  tank  of 
steam  cars.  The  piston  rod  of  a  plunger  pump  is  prolonged 
into  a  cylinder  and  forms  the  piston  rod  of  this  cylinder;  or, 
in  other  words,  a  small  steam  engine  is  fitted  to  the  water  or 
air  pump.  The  ports  of  this  engine  are  fitted  with  valves, 


MOTORS  AND  MECHANISM  215. 

so  that  when  the  steam  is  turned  on  from  the  boiler,  the  valves 
work  automatically,  admitting  and  exhausting  steam  to  and 
from  the  engine,  which  being  thus  set  in  motion  moves  the 
plunger  of  the  pump  backward  and  forward.  As  these  pumps 
are  independent  of  the  engine  driving  the  car,  there  is  no 
necessity  for  the  latter  to  be  set  in  motion  to  fill  up  the  boiler, 
etc. 

Plunger  Pump — This  consists  of  a  piston  working  in  a 
cylinder.  Two  valves  are  fitted — one  at  its  mouth.  When  the 
pump  is  operated  water  is  drawn  in  by  the  suction  of  the 
piston  and  cannot  return.  The  second  valve  may  be  a  non- 
return one,  either  in  the  piston  itself  (in  which  case  the  liquid 
passes  through  the  valve  as  the  piston  moves,  and  during  the 
next  stroke  is  forced  by  the  piston  into  the  required  pipe,  or 
the  second  valve  may  be  placed  in  the  entrance  of  the  dis- 
charge pipe,  in  which  case,  after  the  liquid  is  drawn  by  the 
piston  into  the  cylinder,  the  next  stroke  forces  it  through 
the  valve  in  the  discharge  pipe  against  any  opposing  pressure. 
The  valve  then  returns  to  its  seat  and  prevents  the  liquid  re- 
turning. This  pump  may  be  either  worked  by  hand  or  con- 
nected with  the  engine,  and  is  principally  used  in  steam  cars 
to  supply  the  boiler. 

Hand  Feed  Pump — The  hand  pump  on  a  steam  car  for  sup- 
plying water  to  the  boiler  when  there  is  no  steam,  or  not 
sufficient  steam  to  operate  the  steam  pump,  or  where  the 
steam  pump  has  become  inoperative. 

Double-acting  Pump — A  pump  which  draws  in  and  forces 
out  the  water  or  air  on  both  the  outward  and  inward  stroke 
of  the  piston  or  plunger. 

Force  Pump — See  Plunger  Pump. 
Other  Pumps. 

Air  Pump — Otherwise  '  Pressure  Pump,  and  sometimes 
made  in  the  form  of  a  hand  pump.  Used  for  pressure  feed 
in  gasolene  engines.  A  pump  operated  by  the  engine  to  sup- 
ply air  pressure  to  the  oil  or  gasolene  tank  where  pressure 
feed  is  used  and  where  the  gasolene  tank  is  located  at  a  lower 
level  than  the  carbureter. 


216 


MOTORS  AND  MECHANISM 


Feed  Pump — A  pump  for  feeding  oil,  water,  or  other  liquid. 
The  term  is  generally  applied  to  the  pump  which  feeds  the 
water  to  a  steam  boiler.  Feed  pumps  may  be  of  practically 
any  of  the  types  of  pump  described.  The  illustration  shows 
a  type  of  plunger  feed  pump  sometimes  fitted  to  the  steam 
car.  The  upstroke  or  suction  of  the  ram  A  causes  the  liquid 
to  be  drawn  through  the  check  valve  D.  The  downstroke  of 


FIG.  3— PLUNGER    PUMP. 

the  ram  causes  the  liquid  to  be  forced  through  the  check 
valve  C  into  the  boiler.  G,  G  are  two  plugs  which  allow 
ready  access  to  the  valves  C  and  D.  E  is  a  screwed  cap, 
which  keeps  the  ram  from  leaking  by  means  of  the  stuffing 
F.  B  is  the  connecting  rod  which  actuates  the  ram.  It  is 
also  known  as  a  force  pump. 

Hand  Pump — Any  pump^  worked  by  hand. 
Oil  Pump — The  oil  pump  is  sometimes  operated  by  hand 
and  sometimes  by  the  engine,  and  is  used  to  circulate  lubri- 


MOTORS  AND  MECHANISM  217 

cant  to  the  bearings,  under  force.  It  may  be  either  of  the 
gear  or  rotary  type,  or  of  the  plunger  type,  but  is  seldom  of 
the  centrifugal  type. 

Piston  Pump — A  pump  in  which  the  pumping  is  effected 
by  a  piston  in  a  cylinder  as  distinguished  from  a  centrifugal 
or  a  rotary  gear  pump.  Sometimes  called  a  Suction  Pump. 

Pressure  Pump — See  Air  Pump. 

Two-way  Pump — A  suction  pump  of  the  plunger  type 
which  has  no  automatic  valves.  It  consists  of  a  cylinder  with 
a  piston  inside  it,  the  piston  being  pulled  up  and  pushed  down 
by  hand.  The  bottom  of  the  pump  communicates  by  means 
of  a  two-way  cock  to  the  oil  tank  and  to  the  part  to  be  lubri- 
cated. When  the  cock  is  turned  so  as  to  put  the  pump  cylin- 
der into  communication  with  the  oil  tank,  the  plunger  or 
piston  is  pulled  up  and  oil  flows  into  the  pump  barrel.  The 
cock  is  then  turned  so  as  to  put  the  pump  into  communica- 
tion with  the  part  where  the  oil  is  required,  and  the  plunger, 
being  depressed,  forces  the  oil  to  the  place  requiring  it.  It 
will  be  seen  that  it  not  only  acts  as  a  pump,  but  also  as  a 
measure,  as  the  operator  can  give  a  whole  pump  full,  or 
half  a  pump  full,  or  any  quantity  he  deems  requisite.  In  the 
case  of  some  cars  a  compound  valve  is  used,  operated  by  the 
the  handle  of  the  pump  itself;  an  indicator  on  the  top  of  the 
pump  shows  in  which  direction  the  oil  will  be  directed  so 
that  it  can  be  forced  to  the  crank  case,  the  gear  box,  or  the 
differential,  as  required. 

Tire  Pump — The  ordinary  air  pump  for  inflating  tires. 
Care  should  be  taken  to  lay  in  a  stock  of  "adapters"  in  case  it 
is  found  that  the  nozzle  of  the  pump  does  not  fit  the  air  valve 
of  the  inner  tube.  In  this  case  the  adapter  has  to  be  used,  one 
end  screwing  on  to  the  valve,  the  other  into  the  nozzle  of  the 
pump.  The  necessity  for  these  "adapters"  is  due  to  the  fact 
that  all  pump  nozzles  and  tire  valve  connections  are  not  inter- 
changeable. 


218  MOTORS  AND  MECHANISM 


CHAPTER  XV. 
MOTOR  MISFIRING. 

Missing  Explosions — Whatever  the  cause,  when  a  motor 
misses  on  one  or  more  cylinders  the  trouble  should  be  located 
and  eliminated  with  haste.  The  owner  of  a  four  or  six-cyl- 
inder motor  is  apt  to  overlook  the  fact  that  missing  is  occurr- 
ing or  to  let  it  go,  with  the  idea  that  the  trouble  will  remedy 
itself.  Where  the  missing  occurs  because  of  too  heavy  a  mix- 
ture this  can  be  accomplished  at  increased  speed,  so  as  to  use 
up  the  surplus  of  gas;  but  where  the  cause  lies  in  another 
direction  it  is  a  safe  plan  to  stop  and  take  a  little  time  to  do 
away  with  the  trouble.  Prolonged  missing  may  play  havoc 
with  the  bearings,  connecting  rods  or  some  other  vital  part  of 
the  motor;  it  may  cause  a  rupture  in  the  gears  and  certainly 
is  not  pleasant  to  the  occupants  of  the  car. 

When  a  motor  begins  missing  explosions,  where  before  it 
has  been  running  with  regularity,  the  trouble  can  as  a  rule  be 
traced  to  the  ignition  system  and  it  is  but  natural  this  should 
be  the  first  to  receive  attention  at  the  hand  of  the  operator. 
Even  when  all  things  seem  to  be  in  perfect  working  order  a 
motor  will  continue  to  miss  and  it  is  often  a  puzzle  to  locate 
the  trouble.  As  an  instance,  a  motor  that  had  been  running 
perfectly  right  along  had  been  put  in  a  repair  shop  to  have  a 
new  piece  of  hose  attached  to  the  water  system.  The*  priming 
cocks  were  so  made  as  to  appear  to  be  open  when  shut — and 
vice  versa.  A  shop  hand,  seeing  the  cocks  apparently  open, 
endeavored  to  close  but  in  reality  opened  them.  Naturally 
this  was  overlooked.  The  motor  started  readily,  but  missed 


MOTORS  AND  MECHANISM  219 

except  at  high  speeds,  when  it  could  obtain  sufficient  gas. 
Two  well-versed  men  worked  on  that  motor  for  hours  before 
the  difficulty  was  detected  and  there  was  not  a  thing  from 
carbureter  to  plugs  that  was  not  gone  over  from  one  end  to 
the  other. 

It  is  a  pretty  safe  rule  that  if  the  ignition  system  is  found 
to  be  in  good  order,  the  attention  of  the  operator  should  be 
turned  to  the  carbureter  and  in  all  likelihood  the  trouble  will 
be  located  there!  Still,  there  are  other  reasona  for  a  motoc 
missing  and  they  can  usually  be  found  in  time. 

Ignition. 

(a)  Plugs  Fouled  or  Short-Circuited — When  a  motor  mis'ses, 
determine  which  cylinder  is  at  fault  by  holding  down  the  vi- 
brators of  the  coil,  one  or  two  at  a  time,  so  as  to  cut  out  some 
of  the  cylinders.     When  the  cylinder  that  is  at  fault  is  de- 
termined, look  to  the  plug  and  see  if  it  is  fouled  or  covered 
with  oil  or  if  the  porcelain  is  cracked.    If  after  cleaning  it  ap- 
pears to  be  good,  attach  the  secondary  wire,  lay  the  plug  on 
the  motor  to  form  a  ground  and  turn  the  motor  over  until  that 
cylinder  is  in  contact  and  a  spark  shows  at  the  points  of  the 
plug.     If  the  spark  appears  good — that  is,  purple  and  reason- 
ably large — replace  the  plug  in  the  cylinder  and  run  the  motor. 
If  the  missing  still  occurs,  replace  the  plug  with  a  new  one 
and  try  the  motor  again. 

(b)  Wire  Off — Trace  the  entire  wiring  system  to  see  if  a 
terminal  is  broken,  if  a  connection  is  loose,  if  a  wire  is  off  at 
the  plug,  commutator,  coil,  battery  or  magneto,  and  if  the 
switch  is  clean  and  giving  a  good  contact.     See  that  the  con- 
nections  are   clean   and    the   binding  screws   are    set   down 
tightly. 

(c)  Broken  Wire — On  old  cars  in  particular,  the  wire  within 
the  insulated  covering  is  apt  to  be  broken  through  twisting 
or  excessive  vibration.    A  broken  inside  wire  in  the  secondary 
system  will  not  cause  missing;  this  will  occur  only  in  the 
primary  circuit.     It  is  a  difficult  thing  to  discover,  as  when 
the  motor  is  running  without  load  the  ends  of  the  wire  are 


220  MOTORS  AND  MECHANISM 

apt  to  remain  together  and  form  a  circuit,  whereas  if  the  car 
is  in  motion  the  jolting  of  the  road  may  separate  the  ends 
and  break  the  circuit  occasionally  if  not  all  the  time.  New 
wiring  throughout  is  the  best  remedy  for  such  a  difficulty. 

(d)  Vibrator    Adjustment — Improperly   adjusted   vibrators 
will  cause  a  motor  to  miss.     The  average  owner  is  apt  to  do 
too  much  adjusting  of  the  vibrators  and  to  screw  down  the 
points  to  not  only  make  a  bad  adjustment  but  to  cause  an 
excessive  flow  of  current.    The  tension  of  the  vibrator  spring 
should  be  sufficient  to  cause  a  quick  response  to  the  contact 
but  should  not  be  so  severe  as  to  provoke  a  coarse  sound.    The 
adjustment  of  coils  is  treated  in  another  chapter,  which  should 
be  referred  to. 

(e)  Switch  Loose — A  loose  switch  will  permit  an  irregular 
contact.    It  may  cause  missing  on  one  cylinder  or  may  be  the 
means  of  stopping  the  motor  entirely. 

(f)  Weak  Battery — A  weak  battery  will  not  prevent  start- 
ing and  even  running,  particularly  if  the  mixture  happens  to 
be  just  right  for  the  size  of  the  spark.     The  missing — and  a 
falling  off  in  power — will  become  aggravated  as  the  car  pro- 
ceeds, although  after  the  motor  has  become  heated  and  the 
car  is  under  way  fairly  good  work  will  be  obtained.    .  The 
motor,  however,  will  not  respond  quickly  and  will  tend  to 
choke  if  the  mixture  is  at  all  too  rich.     Where  there  are  two 
sets  of  dry  cells,  connect  them  all  in  series  as  a  temporary 
relief.     If  there  are  two  storage  batteries  and  both  are  weak, 
they  can  be  connected  in  parallel.     It  is  a  good  plan  to  car.ry 
an  ammeter  if  dry  cells  are  used.    A  good  dry  eel1  should  show 
from  15  to  17  amperes  to  be  of  service.    One  bad  dry  cell  will 
pull  down  all  the  others  in  the  series. 

(g)  Dirty  Timer — A  timer  that  has  been  permitted  to  run 
a  long  time  and  to  accumulate  oil,  grease  and  dust  will  in  time 
give  trouble.     A  timer  should  be  cleaned  with  kerosene  and 
rinsed  in  gasolene  to  remove  all  particles  of  dirt.    Care  should 
be  taken  to  thoroughly  evaporate  all  gasolene  before  replacing 
and  starting  the  motor.     The  tinier  should  be  packed  with  a 
good  quality  of  grease  after  it  has  been  cleaned. 


MOTORS  AND  MECHANISM  221 

(h)  Pitted  Vibrator  Points — If  the  points  on  the  vibrator 
spring  or  adjusting  screw  have  been  neglected  for  a  long  time 
they  will  be  found  to  have  become  pitted;  or  there  will  be  a 
little  hole  in  one  side  and  a  little  projection  on  the  other, 
caused  by  the  action  of  the  current  in  passing  from  one  side 
to  the  other.  Where  this  has  occurred  the  battery  wires 
should  be  transposed,  either  at  the  coil  or  at  the  battery,  the 
latter  being  more  simple.  It  will  take  some  time  for  the 
metal  projection  to  leave  that  side  and  go  back  to  the  side 
whence  it  came.  It  is  more  than  likely  this  condition  will  re- 
sult in  the  vibrator  sticking,  and  in  ttiis  case  it  is  advisable  to 
square  up  the  contact  points  with  a  very  fine  file  or  stone. 

(i)  Broken  Vibrator;  Vibrator  Point  Missing — A  vibrator 
will  not  work  in  a  satisfactory  manner  if  the  spring  is  either 
too  weak  or  too  strong;  if  the  spring  is  broken  or  bent;  or  if 
the  points  have  become  very  badly  worn  or  lost.  When  any 
one  or  more  of  the  conditions  are  found  to  exist  the  simplest 
remedy  is  found  in  new  parts,  although  in  an  emergency  a 
vibrator  spring  can  be  straightened  and  made  to  do  service. 
If  the  platinum  point  is  lost  a  new  point  can  be  made  from 
german  silver,  iron  wire,  a  piece  of  silver  from  a  dime  or  al- 
most any  soft  metal,  even  copper.  A  little  piece  can  be  riveted 
to  the  vibrator  so  as  to  permit  the  motorist  to  lose  little  time 
on  the  road. 

(j)  Condenser  Perforated — It  is  not  often  this  occurs.  It 
may  result  from  a  battery  being  used  whose  voltage  is  much 
higher  than  is  intended  for  the  coil.  This  can  be  determined 
by  a  test  made  with  a  galvanometer  and  should  be  made  by  a 
coil  maker  or  coil  repairer.  Where  a  multiple  coil  is  used 
and  one  cylinder  gives  trouble,  the  units  can  be  changed  about 
to  determine  whether  the  coil  is  at  fault.  If,  after  changing 
the  units,  the  same  cylinder  gives  trouble  the  difficulty  cannot 
be  charged  to  the  coil  but.  to  the  plug,  timer,  or  some  other 
part  closely  allied  to  the  particular  cylinder  giving  trouble. 

(k)  Coil  or  Magneto  Wet — If  the.  coil  or  magneto  has  been 
exposed  to  rain,  either  ma)'  have  become  short-circuited.  This 
will  not  only  cause  missing  but,  where  batteries  are  used,  the 


222  MOTORS  AND  MECHANISM 

battery  will  run  down  quickly.  Primary  coils,  where  make- 
and-break  ignition  is  used,  can  easily  be  dried  by  removing 
and  placing  in  an  open  oven  with  a  very  slow  fire.  This  treat- 
ment will  not  do  for  jump  spark  coils,  as  the  heat  will  melt 
the  wax  or  paraffin  and  destroy  the  insulation.  If  a  jump 
spark  coil  becomes  wet,  it  is  advisable  to  send  it  to  the  maker 
to  be  repaired. 

(1)  Wires  Wet — Where  wires — particularly  the  secondary 
— are  run  under  the  frame  of  the  car,  or  otherwise  exposed  to 
water  thrown  by  the  wheels,  a  complete  or  partial  short  cir- 
cuit is  apt  to  result  and  cause  complete  stopping  of  the  motor 
or  a  case  of  violent  missing.  Where  wires  are  exposed  in  this 
manner  the  operator  is  advised  to  preclude  the  possibility  of 
trouble  on  the  road  by  protecting  them  in  some  manner,  such 
as  encasing  them  in  hose. 

(m)  Ground  at  the  Timer — In  old  cars,  where  the  primary 
wire  at  the  timer  has  been  removed  a  number  of  times  and 
has  become  worn,  one  strand  of  the  wire  may  become  sep- 
arated from  the  others  and  touch  some  part  of  the  timer,  caus- 
ing a  short  circuit.  This  is  a  common  occurrence,  particularly 
where  modern  terminals  are  not  used  or  where  the  terminal 
has  been  broken  off.  One  or  more  strands  so  touching  the 
timer  or  other  part,  forming  a  ground,  may  not  be  in  contact 
at  all  times  and  therefore  will  cause  the  missing  to  be  inter- 
mittent. See  that  the  primary  wires  connecting  the,  timer  are 
clear  of  all  metal  and  that  the  insulation  runs  well  up  to  the 
binding  posts.  It  is  a  good  plan  to  tape  the  ends  of  the  wire. 
This  will  prevent  loose  ends  from  causing  a  short  circuit  and 
at  the  same  time  will  assure  a  good  contact  and  prevent  the 
possibility  of  the  wire  becoming  detached  from  the  binding 
post. 

(n)  Timer  Contact  Destroyed — Missing  is  often  caused  by 
a  poor  contact  at  one  of  the  points  of  the  timer,  either'  from 
dirt  or  oil  or  from  wear  on  some  of  the  parts.  In  timers 
where  a  roller  contact  is  used,  the  roller  will  jump  over  the 
contact  piece  in  the  insulated  part,  in  part  if  not  wholly,  and 
will  give  such  a  short  contact  as  to  prevent  sufficient  current 


MOTORS  AND  MECHANISM  223 

from  passing  through  the  circuit.  This  can  frequently  be  de- 
tected by  the  motor  running  well  after  the  plugs  have  been 
cleaned  and  missing  as  soon  as  they  have  become  fouled.  It 
is  possible  to  raise  the  points  slightly  so  as  to  make  the  con- 
tact longer  when  the  roller  passes  over  them.  Care  must  be 
used,  however,  to  see  that  the  points  are  not  raised  so  far  as 
to  cause  an  edge  to  be  felt  when  the  finger  is  run  around  the 
path  of  the  roller  on  the  fiber  lining.  If  a  contact  piece  does 
become  worn,  the  timer  can  be  taken  to  a  machine  shop  and 
turned  down  on  the  inside  sufficiently  to  cause  the  inside  sur- 
face to  be  perfectly  even. 

Carbureter — Mixture. 

(a)  Mixture  Too  Lean — Missing,  particularly  at  high  motor 
speed,  when  the  motor  is  running  idle,  is  generally  caused  by 
a  lack  of  gasolene  or  surplus  of  air,  and  is  accompanied 'by  a 
popping  back  in  the  carbureter.    This  is  where  the  float  level 
is  correct.     If  the  float  level  is  too  low,  the  same  effect  will 
be   noticeable.      Either  a   little    more    gasolene   through   the 
medium  of  the  needle  valve  or  a  trifle  less  air  will  generally 
effect  a  cure.     See  Adjustments,  under  Carbureters. 

(b)  Mixture  Too  Rich — Too  much  gasolene  or  too  little  air 
will  cause  the  motor  to  miss,  to  be  sluggish,  to  cause  the  car 
to  jerk  and  to  pick  up  slowly.    It  will  also  overheat  the  motor. 
At  high  speed  this  will  not  be  so  noticeable,  as  the  motor  will 
use  the  excess.     To  determine  this,  throw  out  the  clutch  and 
race  the  motor.     If  it  runs  evenly  under  such  conditions,  it  is 
strong  evidence  that  the  mixture  is  too  rich  and  the  carbureter 
should  be  readjusted.     See  Adjusting  Carbureters,  under  Car- 
bureter. 

(c)  Air  Leak  in  Manifold — If  the  nuts  or  bolts  holding  the 
intake  manifold  to  the  motor  become  loosened  and  permit  a 
slight  leak  of  air,  the  motor  will  be  hard  to  start  and  will  miss 
badly   except   possibly   at   high   motor   speed,   in   which    case 
there  will  be  a  sufficient  charge  of  gas  taken  into  the  cylinder. 
Where  an  air  leak  is  the  trouble  the  motor  will  not  throttle 
.  well  and  will  not  develop  power  under  heavy  work.    If  tight- 


224  MOTORS  A^D  MECHANISM 

ening  the  nuts  or  bolts  does  not  effect  a  remedy,  a  gasket  of 
some  thin  material,  or  even  shellac,  will  be  required. 
r  (d)  Priming  Cocks  Open— Symptoms  the  same  as  in  the 
case  above  cited.  The  motor  will  be  hard  to  start  and  the 
motor  speed  under  no  load  will  be  excessive.  The  running  of 
the  motor  will  be  accompanied  by  a  hissing  sound,  caused  by 
the  inrush  of  air. 

(e)  Restricted   Gas  Supply— Where  the  throttle  is  so  set 
as  to  restrict  the  supply  of  gas,  the  motor  will  miss — some- 
times only  occasionally,  according  to  the  supply  of  gas.     The 
throttle  should  be  so  set  as  to    permit    the    motor    to    run 
regularly.    If  it  runs  at  excessive  speed,  the  mixture  is  at  fault 
and  should  be  adjusted. 

(f)  Cold  Motor — No  matter  what  the  nature  of  the  mixture, 
a  motor  will  miss  when  excessively  cold  and  continue  to  do  so 
until  it  has  become  heated.   Gasolene  will  not  volatilize  readily 
when  cold,  and  propagation  of  the  gases  is  slow.    Where  the 
motor  is  cold,  also,  there  will  be  a  firing  in  the  carbureter,  be- 
cause of  slow  combustion.    When  the  motor  is  cold  and  miss- 
ing takes  place,  the  ignition  can  be  advanced  considerably  past 
the  normal  point  until  the  motor  has  become  warmed. 

(g)  Valve  Spring  Weak  or  Broken — When  a  valve  spring 
is  too  weak  to  permit  the  valve  to  seat,  or  is  broken,  causing 
the  same  trouble,  the  motor  will  naturally  miss  because  of  its 
inability  to  hold  gas  in    the    particular  cylinder  having  the 
troublesome  spring.     If  the  valve  spring  is  broken,  an  iron 
washer  may  be  placed  between  the  broken  ends — and  over  the 
valve  stem,  of  course — and  the  motor  will  run  as  well  as  ever. 
Care  must  be  exercised  to  prevent  the  washer  from  binding 
at  any  point.     Where  the  spring  is  excessively  weak,  washers 
may  be  used  to  place  a  tension  on  the  valve  spring. 

(h)  Valve  Stem  Bent — A  bent  valve  stem  will  cause  the 
valve  to  stick  and  hold  open,  permitting  loss  of  compression 
and  preventing  suction  of  gas.  The  valve  must  be  taken  out 
and  the  stem  straightened.  In  an  emergency  this  can  be 
done  on  the  road,  although  it  is  a  mechanic's  work.  In  case 
of  a  roadside  job,  the  stem  should  be  laid  on  a  piece  of  wood 


MOTORS  AND  MECHANISM  225 

which  is  slightly  concave.  Another  piece  of  wood  should  be 
interposed  between  the  stem  and  hammer,  otherwise  the  stem 
will  be  so  marred  as  to  be  unable  to  pass  through  the  valve 
stem  guide.  The  blows  to  straighten  should  be  light,  followed 
by  close  inspection.  When  the  stem  will  work  freely  in  the 
guide,  and  the  valve  seats,  it  can  be  used.  Straightening  a 
stem  is  apt  to  unseat  the  valve  and  this  may  need  regrinding. 

(i)  Valve  Stem  Sticking — A  valve  stem  may  stick  from 
being  fouled  with  carbon  or  gummed  with  oil,  in  which  case 
all  that  is  necessary  is  to  clean  carefully  with  kerosene  and 
gasolene.  Do  not  oil  valve  stems. 

(j)  Valve  Not  Seating — This  is  not  usually  a  cause  for  a 
motor  missing.  It  will  interfere  with  obtaining  a  correct  car- 
bureter adjustment,  however,  and  a  .poor  carbureter  adjust- 
ment will  cause  a  motor  to  miss,  so  that  indirectly  it  may 
be  the  cause  of  the  trouble.  The  remedy  for  this  is  to  regrin'd 
the  valve  until  it  seats  perfectly. 


226  MOTORS  AND  MECHANISM 


CHAPTER  XVI. 
NOISES  IN  THE  MOTOR. 

Pounding  and  Knocking— It  is  not  always  easy  to  distin- 
guish between  these  two  terms — "pounding"  and  "knocking" 
— in  connection  with  a  motor.  A  pound  may  be  described  as 
a  deep-toned,  muffled  sound,  while  a  knock  is  sharp  and  is  ac- 
companied by  more  or  less  of  a  metallic  ring.  The  presence 
of  either  calls  for  immediate  investigation  and  elimination, 
as  to  be  permitted  to  continue  might— ^and  undoubtedly  would 
— cause  almost  irreparable  damage  or  damage  that  could  be 
rectified  only  at  considerable  financial  expense  and  the  laying 
up  of  the  car  for  a  few  days. 

Pounding. 

(a)  Loose  Connecting  Rod — Remove  bottom  half  of  crank 
case  or  side  plates,  according  to  motor  design,  and  feel  con- 
necting rod  and  crankshaft  bearing  for  looseness.  If  there 
are  shims  between  rod  and  cap,  remove  one  or  more  so  as 
to  bring  the  cap  close  against  the  shaft.  This  will  effect  a 
temporary  repair,  but  as  soon  as  possible  the  connecting  rod 
and  cap  should  be  scraped  to  insure  a  good  fit.  Do  not  fit 
the  parts  so  close  as  to  cause  them  to  bind ;  a  little  play  will 
be  better.  When  replacing,  rub  on  plenty  of  lubricating  oil; 
never  assemble  wearing  parts  dry. 


MOTORS  AND  MECHANISM  227 

(b)  Loose    Bearing — Usually  the  back  bearing.      A  loose 
bearing  is  hard   to  locate  and  is  usually  found  through  the 
process  of  elimination.     A  piece  of  ^4-inch  steel   wire,  one 
end  placed  between  the  teeth  and  the  other  over  the  bearing 
will  usually  locate  the  trouble  while  the  motor  is  running.    If 
the  pound  is  bad,  have  the  trouble  eliminated  at  a  good  repair 
shop.     Such   trouble   develops    slowly    and    seldom    prevents 
one  from  continuing  on  a  journey  of  reasonable  length.  Where 
a  bearing  is  loose  the  noise  is  more  noticeable  at  slow  motor 
speeds.     In  cases  of  this  kind  run  the  motor  moderately. 

(c)  Loose  Flywheel — Particularly  common  where  the  fly- 
wheel is  keyed  to  the  crankshaft  and  not  easy  to  determine. 
More  apt  to  show  when   motor  is  running  idle  than  when 
clutch  is  engaged.    Where  flywheel  is  bolted  to  a  flange  made 
integral  with  crankshaft,  tighten  nuts  on  bolt   ends ;  where 
keyed  on,  drive  in  key,  using  soft  iron  or  brass  bar  between 
key  and  hammer. 

(d)  Preignition — Carbon  in  cylinders,  which  keeps  aglow 
from  heat  of  the  explosion,  will  ignite  the  incoming  gas  before 
the  piston  has  passed  the  top  of  the  compression  stroke.    This 
tends  to  drive  the  piston  downward  and  against  the  momen- 
tum of  the  flywheel,  thus  causing  a  pound.    It  tends  to  spring 
the  crankshaft  and  wear  the  bearings.   The  use  of  kerosene  or 
carbon  remover  may  remove  the  trouble  to  some  degree  tem- 
porarily, but  the  surest  way  is  to  take  the  carbon  out  through 
the  valve  cage  holes  in  valve-in-the-head  motors  or  by  re- 
moving the  cylinders  in  other  types.     Excessive  lubrication 
causes  carbon  deposits. 

(e)  Shaft  Sprung — A  loose  bearing,  preignition  or  advanced 
spark  may  cause  a  crankshaft  to  spring  slightly  out  of  true. 
It  can  be  determined  only  by  removing  the  cylinders  and  top 
half  of  the  crank  case  and  revolving  the  crankshaft  and  test- 
ing with  a  surface  gauge  to  determine  trueness.     To  remedy 
such  a  disturbance  requires  the  work  of  a  thorough  mechanic ; 
better  still,  send  it  to  the  factory  which  made  the  motor. 

(f)  Lost  Motion — Looseness  in  any  of  the  working  parts 


228  MOTORS  AND  MECHANISM 

will  cause  a  pound  and  can  be  located  only  by  patient  search 
and  through  the  process  of  elimination. 

(g)  Misfiring — One  or  more  cylinders  misfiring  will  cause 
a  decided  pound.  Locate  the  cylinder  and  stop  the  missing. 
See  chapter  devoted  to  missing. 

(h)  Unequal  Compression — One  cylinder  with  compression 
weaker  (or  greater)  than  the  other  will  cause  a  pound  through 
being  out  of  balance.  Try  each  cylinder  for  compression  and 
endeavor — through  grinding  values,  tightening  plugs  and  valve 
caps — to  bring  all  to  an  equality. 

(i)  Restricted  Exhaust — A  motor  which  has  been  overlubri- 
cated  and  permitted  to  smoke,  will  foul  the  exhaust  pipe  and 
muffler,  causing  decided  back  pressure  and  creating  a  pound. 
If  there  is  a  muffler  cut-out,  open  this  to  determine  if  the 
trouble  lies  here.  Clean  the  muffler  by  dissembling,  "if  possi- 
ble, or  by  soaking  in  kerosene  for  several  hours.  Be  careful 
that  all  traces  of  kerosene  are  gone  before  assembling  and 
starting  the  motor.  The  kerosene  may  be  washed  out  with 
gasolene,  and  should  be  left  to  stand  over  night  so  the  oils 
will  drain  out. 

(j)  Loose  Wristpin — Possible  but  not  likely  cause.  De- 
termined by  disconnecting  the  connecting  rod  from  the  crank- 
shaft and  moving  up  and  down.  If  loose,  new  wristpin  bush- 
ings in  the  cylinder  constitute  the  remedy. 

(k)  Connecting  Rod  End  Slap— Most  makers  provide  for 
about  ^-inch  end  play  on  the  crankshaft  end  of  the  connect- 
ing rod.  Occasionally  the  bearing  becomes  rounded,  so  that 
on  the  impulse  stroke  the  rod  slips  on  the  crankshaft  and 
causes  a  slap  on  the  end.  It  is  disagreeable  and  indicates  that 
the  bearing  needs  attention.  It  is  likely  to  accompany  a  loose 
connecting  rod  bearing  and  can  be  determined  in  the  same 
manner.  Removing  shims,  however,  will  not  remedy  the 
matter ;  the  bearings,  if  rounded,  must  be  scraped  until  they  are 
square  with  the  crankshaft. 

(1)  Loose  Cylinder— Place  the  hand  so  as  to  cover  the  base 
of  the  cylinder  and  part  of  top  half  of  the  crank  case.  If  loose 
it  will  be  felt.  Set  down  nuts  holding  cylinder  to  base.  Do 


MOTORS  AND  MECHANISM  229 

this  occasionally  as  a  good  rule  to  follow  on  general  prin- 
ciples. 

(m)  Loose  Crank  Case — May  be  loose  where  bolted  to 
frame ;  bottom  half  may  be  loose.  Either  determined  by  ex- 
amination and  holding  hand  on  parts  when  motor  is  running. 
Tighten  nuts  to  remedy. 

(n)  Nut  or  Bolt  in  Crank  Case — A  nut  might  loosen,  drop 
to  the  bottom  of  the  crank  case  and  the  connecting  rod  hit 
but  pass  same.  This  is  unlikely,  as  in  all  probability  striking 
it  would  break  the  case  instantly. 

Knocking. 

(a)  Spark  Advanced — This  causes  the  gas  to  ignite  before 
the  piston  has  reached  the  top  of  the  compression  stroke — it 
is  preignition  and  causes  a  decided  knock.     Particularly  no- 
ticeable if  motor  speed  is  slow,  as  in  ascending  a  grade,  and 
spark  has  not  been  retarded.     Will  cause  bearings  to  wear. 
Spark  should  be  kept  in  close  relation  to  speed  of  the  motor. 

(b)  Overheating — Lack  of  water  passing  through  the  water 
jackets  causes  the  metal  to  expand  and  bind  the  reciprocating 
parts.     Water  supply  may  be  short  or  not  circulating.     Ex- 
cessive use  of  oil  might  permit  a  short  run  only. 

(c)  Lack  of  Oil — Very  common  cause  for  knocking.    Motor 
will  bind  if  stopped.     In  this  case  work  a  small  quantity  of 
kerosene  into  the  cylinders  through  plug  holes-  and  turn  motor 
by  hand.     Then  work  in   lubricating  oil  in  small   quantities 
until  motor  is  free.    See  that  crank  case  has  oil  and  that  lubri- 
cator is  working.  • 

(d)  Piston  Ring  Stuck — Caused  by  over-lubrication  and  con- 
sequent carbon  deposits  under  rings.     Remove  plugs,  inject 
two  tablespoonfuls  kerosene  in  each  cylinder,  permit  it  to  stand 
over  night,  'turn  motor  vigorously  by  hand— with  plugs  re- 
moved— to  eject  surplus  kerosene. 

(e)  Preignition — Also  causes  knock.     See  under  head  of 
Pounding,  above. 

(f)  Push  Rod   Clearance — Ends  of  valve  stems  and  push 
rods — and   rocker  arms   in   valve-in-head   motors — will   wear, 


230  MOTORS  AND  MECHANISM 

causing  too  much  clearance  and  a  knock.  Clearance  should 
be  adjusted  according  to  maker's  instructions.  If  too  close  or 
too  far  apart,  the  time  of  opening  and  closing  the  valves  is 
materially  affected. 

.  (g)  Timer  Slipped — Occasionally  the  commutator  will  slip 
and  thereby  automatically  advance  the  spark.  Thus  the  neces- 
sity for  knowing  where  the  timer  should  be  set  on  the  cam 
shaft.  Usually,  of  course,  the  tendency  is  to  retard  the  spark 
where  the  timer  has  slipped. 

(h)  Loose  Cam  or  Cam  Shaft — Loose  cams  are  unusual 
now,  as  cams  are  cut  integral  with  the  camshaft.  Shaft  where 
keyed  to  gear  may  be  loose,  or  gears  may  be  worn  to  cause 
slight  knock.  Not  likely.  If  key  is  loose,  drive  in ;  if^gears  are 
worn,  replace,  as  much  play  affects  the  time  of  valve  action 
and  ignition. 

(i)  Loose  Pump  or  Magneto  Pin — Pump  shafts  are  fre- 
quently driven  by  a  pin ;  magnetos  are  thus  driven  only  occa- 
sionally. In  pump,  if  packing  gland  is  not  tight,  driving 
against  pin  if  loose  will  cause  very  slight  knock. 

(j)  Loose  Magneto — Fastening  of  magneto  may  loosen  and 
cause  knock. 

(k)  Loose  Oiler  Mechanism — Where  mechanical  lubricator 
is  driven  by  ratchet  or  eccentric  mechanism,  a  worm  or  loose 
part  will  cause  a  knock,  which  can  be  removed  only  by  taking 
up  the  wear. 

(1)  Fan  Hitting — Bent  fan  blades  may  hit  radiator; 
straighten.  Set  screw  may  strike  belt;  put  in  shorter  one. 
Belt  fastener  may  slap  pulley ;  replace. 

(m)  Rocker  Shaft  Loose — In  make-and-break  ignition, 
rocker  shaft  or  pawls  may  be  deranged  or  loose  or  worn.  Go 
over  and  tighten  or  replace. 


•   MOTORS  AND  MECHANISM 


CHAPTER  XVII. 
MOTOR  OVERHEATING. 

Overheating  of  the  motor  may  result  from  a  number  of 
causes,  which  are  taken  up  in  the  order  of  probable  frequency. 
Here  appears  the  necessity  for  knowing  the  maker's  scheme 
of  timing  the  spark  and  the  setting  of  the  valves,  inasmuch 
as  these  points  may  enter  into  the  cause  of  heating. 

Modern  motors  are  not  prone  to  overheating  troubles  from 
lack  of  proper  design ;  they  will  cause  trouble  if  some  adjust- 
ment becomes  disarranged  or  the  operator  does  not  give  some 
attention  to  this  very  important  matter.  Heating  may  be 
divided  into  several  classes,  but  four  will,  when  properly  sub- 
divided, cover  the  majority  of  cases.  In  case  of  an  overheat- 
ing motor,  look  for  the  trouble  in  the  order  given  below: 

Radiation. 

Lack  of  Water — Examine  the  tank  and  fill  with  clean, 
strained  water.  Soft  water  is  preferable.  Run  the  motor  to 
remove  the  air  in  the  radiator  and  pipes  and  keep  putting 
in  .water  until  filled. 

Fan  Not  Working — (a)  Belt  lost — Make  temporary  belt 
from  clothesline,  sewing  machine  belt,  wire  spring  if  long  one 
can  be  secured,  or  from  shoe  laces.  After  using  for  a  while,, 
see  that  stretch  is  taken  up. 

(b)  Belt  stretched — Take  up  slack  by  removing  from  one 
pulley  and  twisting,  securing  ends  as  originally. 

(c)  Belt   coated   with   oil — Remove   and   wash   with   gaso- 
lene; for  temporary  job  rub  on  fine  sand,  being  careful  that 
none  finds  access  to  the  working  parts  of  the  motor  or  other 
wearing  parts. 

(d)  Tightener  slipped — Reset  nut  or  set-screw ;  if  either  is 


232  MOTORS  AND  MECHANISM 

broken,  use  a  piece  of  wire  to  hold  tightener,  attaching  wire 
to  some  part  of  the  bonnet  or  motor. 

Pump — (a)  Pin  through  driving  shaft  sheared  off — The  pin 
can  be  replaced  temporarily  at  least  while  on  the  road  by  a 
wire  nail,  piece  of  heavy  wire,  cotter  pin  or  small  bolt.  Where 
this  temporary  repair  has  been  made  with  a  makeshift  pin  of 
soft  metal  a  frequent  examination  should  be  made  to  see  that 
the  substitute  is  holding. 

(b)  Packing  gland  loose — If  packing  material  has  become 
lost,  replace  with  a  piece  of  candle  wicking  soaked  iji  ©il  or 
grease.     Strips  from  a  handkerchief  will  do  on  a  pinch.    Re- 
place the  gland  and  screw  up  fairly  tight.     If  the  packing 
gland  is  loose  it  is  apt  to  cause  an  air  leak  and  prevent  the 
pump  from  doing  full  duty. 

(c)  Gears  worn — When  the  gears  in  a  gear  pump  or  the 
vanes  in  a  vane  pump  become  worn  it  means  a  repair  shop 
job  of  turning  down  the  plates  so  the  sides  will  be  brought 
closer  to  the  gears.    This  trouble  is  not  apt  to  develop  sud- 
denly or  on  the  road  unless  on  a  long  tour. 

(d)  Pump  clogged — Some  pumps  are  protected  by  a  screen, 
which  in  time  becomes  clogged  with  pieces  of  rubber  disin- 
tegrated from  the  hose  or  by  sediment  from  the  radiator.    This 
will  stop  the  circulation  and  should  be  removed. 

Other  Causes. 

Radiator  Fouled — Where  water  containing  lime  has  been 
used  a  scale  will  form  and  if  not  removed  frequently  will  cause 
severe  overheating.  It  is  well  to  clean  the  radiator  three  or 
four  times  a  season  on  suspicion.  A  scale  remover  can  be 
purchased,  or  a  mild  solution  of  lye  can  be  used.  Dissolve 
half  a  small  can  of  lye  in  a  pail  of  water,  strirring  until  all  is 
dissolved.  Strain  and  pour  in  the  radiator.  Run  the  motor 
for  a  few  moments.  Let  stand  10  minutes  and  drain  off.  Fill 
with  clean  water,  run  the  motor  and  drain.  Repeat  the  clean- 
water  operation  four  or  five  times.  Do  not  permit  the  lye 
water  to  touch  paint  or  varnish,  else  the  latter  will  be  ruined. 
It  must  be  remembered  that  the  lye  will  sooner  or  later  de- 


MOTORS  AND  MECHANISM  233 

stroy  the  rubber  hose,  which  must  be  renewed  as  occasion 
seems  to  demand. 

Clogged  Radiator — To  determine  whether  the  radiator  is 
clogged,  disconnect  the  lower  pipe — the  one  running  to  the 
pump — and  see  if  the  water  flows  freely.  If  not,  the  radiator 
is  clogged.  To  remedy  this  attach  a  hose  and  resort  to  slight 
pressure  to  remove  the  obstruction.  If  water  pressure  will 
not  suffice,  about  25  pounds  of  air  or  steam,  the  former  pre- 
ferred, will  in  all  probability  do  the  work. 

Pipes  Restricted — It  is  possible  in  replacing  water  pipes  and 
using  gaskets  to  restrict  the  circulation  of  water  if  the  gaskets 
are  misplaced  a  trifle.  Placing  gaskets  should  be  done  with 
care. 

When  replacing  hose  it  is  possible  to  ruffle  the  inside  end 
with  the  edges  of  the  metal  pipes  and  to  cause  pieces  of  rub- 
ber to  become  dislodged.  This  should  be  avoided  if  the  pipes 
are  not  to  be  clogged. 

Imperfect  Air  Circulation — Where  the  fan  is  formed  by 
webs  in  the  flywheel  the  bonnet  and  pan  under  the  motor 
must  be  practically  airtight  in  order  that  the  air  may  be 
pulled  through  the  radiator  and  thus  perform  its  duties  of 
cooling.  Holes  in  the  pan  or  open  joints  in  the  radiator  will 
prevent  the  proper  circulation  of  air  and  should  be  stopped 
up  in  any  manner  possible. 

Where  a  motor  is  so  designed  that  proper  vent  for  the  crank 
case  cannot  be  secured,  heating  may  result;  this  is  not  apt  to 
occur  in  modern  motors,  however. 

Late  Ignition. 

(a)  Timer  slipped — Timers  are  frequently  secured  to  the 
end  of  the  camshaft  or  to  a  vertical  shaft  driven  through  bevel 
gears  by  the  camshaft,  by  means  of  set  screws.    If  there  is  a 
bind  in  the  wearing  parts  of  the  timer  and  the  set  screw  be- 
comes loosened  the  shaft  will  slip  away  from  the  proper  posi- 
tion and  the  spark  will  become  retarded,  causing  overheating 
and  non-responsiveness  on  the  part  of  the  motor. 

(b)  Gears  misplaced — Where  a  vertical  shaft  carrying  the 
timer  is  driven  through  bevel  gears  from  the  camshaft,  it  is 


234  MOTORS  AND  MECHANISM 

possible  in  reassembling  to  misplace  these  gears  one  or  two 
teeth  and  thus  cause  the  ignition  to  be  retarded  and  cause 
heating  or  to  advance  the  ignition  too  much  and  cause  a 
knock  in  the  motor. 

It  is  well  to  have  the  timer  and  the  gears  marked  so  they 
can  be  correctly  replaced. 

Carburation — Too  rich  a  mixture  will  quickly  cause  overheat- 
ing, and  some  good  authorities  claim  that  overheating  can  re- 
sult from  too  lean  a  mixture,  although  the  author  has  never 
known  of  a  case.  At  any  rate,  it  is  just  as  well  to  have  correct 
mixture  as  too  lean  or  too  rich.  Too  rich  a  mixture  can  be 
detected  by  the  odor  of  unburned  gasolene  and  by  black 
smoke  from  the  exhaust.  Too  lean  a  mixture  can  be  detected 
usually  by  a  popping  back  into  the  carbureter. 

Additional  Causes  of  Overheating. 

Tight  bearings  or  tight  piston,  resulting  from  either  too 
close  a  fit  or  a  lack  of  lubrication,  will  cause  severe  ,overheat- 
ing  as  a  result  of  a  more  liberal  supply  of  gas  to  make  the 
motor  do  its  work.  If  it  is  found  this  is  the  trouble  a  super- 
abundance of  lubrication  will  probably  effect  a  cure,  although 
it  may  result  in  sooting  the  plugs  and  possibly  carbonizing 
the  cylinders. 

If  the  exhaust  pipe  and  muffler  become  more  or  less  re- 
stricted as  a  result  of  carbon  deposits  arising  from  an  exces- 
sive use  of  lubricating  oil  in  the  motor,  it  will  cause  a  back 
pressure  and  consequently  overheating  if  not  a  stopping  of  the 
motor.  This  can  be  determined  by  using  a  muffler  cut-out, 
if  one,  is  fitted,  to  give  perfectly  free  exit  to  the  exhaust  gases. 
Both  muffler  and  exhaust  pipe  should  be  removed  at  the  end 
of  a  season  and  thoroughly  cleaned. 

When  the  valves  become  disarranged  through  error  in  re- 
assembling and  the  exhaust  is  not  permitted  to  find  its  way 
out  of  the  cylinder  at  the  time  designed,  the  prolonging  of 
the  time  for  holding  the  exhaust  will  cause  overheating;  thus 
the  necessity  for  knowing  the  correct  valve  setting  and  having 
the  valves  set  properly. 


MOTORS  AND  MECHANISM 


CHAPTER  XVIII. 
ELECTRIC  MOTORS. 

The  electric  car  is  the  ideal  motor  car  in  certain  respects, 
says  an  authoritative  writer  on  the  subject,  and  the  less  per- 
fect in  certain  others.  The  chief  defect  is  in  the  means  of 
supplying  energy  to  the  motor.  The  chief  perfection  is  in 
the  means  of  applying  the  energy  and  controlling  it  which 
the  motor  itself  affords. 

The  continuous  torque,  perfect  balance  and  high  speed  of 
which  the  motor  is  capable  diminish  the  stresses  on  the  trans- 
mission chains  or  gear  and  effect  an  economy  of  weight  by 
dispensing  with  flywheels,  gear,  etc.,  which  is,  however,  not 
sufficient  to  counterbalance  the  excessive  weight  required 
by  the  storage  cells  if  these  are  to  have  any  length  of  life 
and  to  travel  for  distances  comparable  to  the  mileage  of 
gasolene  cars.  Unlike  the  gasolene  engine,  the  electric  motor 
may  be  made  to  turn  at  a  constant  speed  regardless  of  the 
gradient,  or  at  will  at  an  approximately  constant  rate  of 
working  no  matter  what  speed,  within  limits.  These  qualities 
afford  immense  advantages  which  are  unobtainable  with  the 
explosion  engine,  though  they  are  reached  to  a  certain  ex- 
tent with  those  steam  engines  which  allow  a  variable  cut-off. 
To  enable  the  gasolene  engine  to  work  at  full  power  while 


236  MOTORS  'AND  MECHANISM 

the  car  travels  at  a  low  speed,  gear  which  is  changed  brusquely 
in  steps  is  resorted  to,  and  to  enable  the  gasolene  engine  to 
work  at  a  constant  speed,  no  matter  what  may  be  the  effort 
required  by  the  road  gradients,  requires  an  efficient  system 
of  governing,  and  further  makes  it  necessary  that  the  engine 
shall  be  of  such  large  dimensions  as  to  be  able  to  permanently 
give  what  may  be  only  a  momentary  excess  of  load. 

The  electrical  connections  to  the  motor,  controller  and 
batteries  of  an  electric  car,  though  they  require  larger  con- 
ductors than  the  electrical  connections  for  the  ignition  of  a 
gasolene  car,  are  in  most  cases  not  appreciably  more  compli- 
cated and  in  many  cases  are  more  accessible.  This  means  in 
practice  that  the  electric  car  is,  to  a  degree  which  is  not  al- 
ways appreciated,  simpler  than  the  gasolene  car,  or,  in  other 
words,  the  ordinary  gasolene  car  frequently  carries  in  minia- 
ture the  whole  of  the  complication  of  the  electric  vehicle  with 
an  internal  combustion  engine  and  a  gear-box  in  addition. 

Turning  from  the  perfections  of  the  motor  and  passing  to 
the  difficulties  which  attend  any  attempt  to  make  portable  a 
supply  of  electric  energy,  we  find  a  far  less  hopeful  state  of 
affairs. 

The  comparison  between  an  electric  car  and  the  more  usual 
type  of  motor  car  driven  from  an  explosion  engine  may  be 
briefly  summarized  as  follows : 

Advantages  of  the  Electric  Motor  for  Automobiles — i.  A 
rotary  engine  of  light  weight  giving  a  large  torque  at  small 
speeds,  able  to  stand  overloads. 

2.  High  internal   efficiency  of  the  combination  of  motor 
and  its  speed-reducing  gear,  if  any. 

3.  A  cheap  mechanical  equipment  for  speed  control,  owing 
to   the   possibility   of   dispensing   with   gear   and   clutch    for 
change  speeds. 

4.  Cheap   maintenance,   cheap   lubrication,   freedom   from 
breakdown. 

5.  Absence  of  lubrication  troubles,  valve  troubles,  oil,  dirt, 
smell,    water-circulating   troubles,    pumps,    cooling   radiators, 
pipes,  inflammable  material  in  store,  etc. 


MOTORS  AND  MECHANISM  237 

6.  Extreme  simplicity — three  parts  only;  motor,  controller 
and  battery;  ease  of  rinding  faults,  and  ease  of  measuring 
power  used. 

7.  Cheap   and   clean  housing;   no  fire   risk  compared   to 
gasolene  risks. 

8.  Ease  of  manipulation;  flexibility  of  control  owing  to 
the  absence  of  mechanical  links,  bell  cranks,   etc.,   allowing 
controller  to   be  placed  anywhere  regardless  of  position  of 
motor. 

9.  Thoroughness  of  control:  reverse  for  all  speeds,  motor 
usable  as  brake,  yet  absorbing  little  power  when  driven  by 
the  road  wheels  when  coasting. 

10.  No  exhaust  noises,  backfire  or  muffler  explosions. 

11.  Certainty  and  ease  of  starting  from  the  driver's  seat 
by  a  switch  only. 

Disadvantages — i.  Weight  of  batteries,  which  more  than 
counter-balance  the  advantage  here  gained  on  the  motor. 

2.  Cost  of  battery,  which  outweighs  the  cheapness  of  the 
electric  motor  and  the  cheapness  of  mechanical  equipment. 

3.  Inefficiency  of   battery,  which  outweighs  the  efficiency 
of  the  motor  and  absence  of  gear  losses. 

4.  Rapid   depreciation   of   battery,   which   outweighs    the 
small  cost  of  upkeep  of  motor,  and  economies  due  to  having 
no  clutches  or  gear. 

5.  Acid  fumes  and  spillage,  which  may  be  set  against  the 
absence  of  smell  and  absence  of  oiling,  and  the  depreciation 
by  way  of  dirt  which  oil  brings. 

6.  Loss  of  time  for  recharging,  say  one-quarter  of  the  use- 
ful time. 

7.  Limited  number  of  charging  stations  and  distance  possi- 
ble on  one  charge. 

8.  Occasional  necessity  for  losses  in  charging  due  to  va- 
riety of  pressure  at  different  stations. 

It  will  be  noticed  that  the  first  among  the  disadvantages  is 
the  weight  of  batteries,  and  this,  taken  in  conjunction  with 
the  volume  they  occupy,  their  liability  to  rapidly  depreciate, 
and  their  small  capacity  from  the  point  of  view  of  the  num- 


238  MOTORS  AND  MECHANISM 

ber  of  miles  of  country  which  can  be  covered  on  one  charge, 
alone  explains  the  slow  progress  made  by  a  vehicle  offering 
so  many  advantages.  Another  disadvantage  of  storage  bat- 
teries is  the  serious  effect  resulting  from  short-circuiting  the 
cells.  No  automatic  protection  which  can  be  afforded  to  the 
batteries  can  be  looked  upon  as  otherwise  then  remunerative 
expenditure,  and  the  lack  of  success  which  has  from  time  to 
time  troubled  those  who  have  instituted  electric  vehicle  serv- 
ice is  very  largely  ascribable  to  the  lack  of  such  protection. 

Distance  Traveled — The  average  electric  automobile  fitted 
up  as  a  pleasure  carriage  for  town  work  is  designed  to  go, 
when  new,  about  40  miles  upon  one  charge  of  the  battery. 
In  practice,  says  the  authority  quoted  above,  it  is  found  that, 
with  the  loss  of  battery  capacity  with  use  and  vibration,  the 
occasional  high  discharge  rates  required  up  hills,  and  fre- 
quent re-starting  and  stopping  in  city  traffic,  the  average 
distance  which  may  be  covered  day  after  day  by  such  a  car 
is  30  miles,  with  the  possibility  of  occasionally  doing  a  little 
more.  Any  attempt  to  largely  increase  this  distance  (and 
many  such  attempts  have  been  made  -for  the  purposes  of 
advertisement  of  new  batteries,  etc.)  has  resulted  in  either 
so  large  an  increase  of  the  weight  of  the  car  that  the  pro- 
portion of  deadweight  to  useful  weight  has-  become  excessive, 
and  the  wear  of  the  rubber  tires  has  very  greatly  increased 
their  cost  of  upkeep,  or  the  battery  has  received  such  heavy 
discharges  in  proportion  to  its  capacity  that  its  life  is  greatly 
shortened  and  the  cost  of  renewals  augmented  to  a  point 
which  is  unsatisfactory  in  ordinary  routine  work,  however 
effective  as  an  advertisement  such  long  runs  may  be. 

Consumption  of  Electrical  Energy — Roughly  speaking,  it 
may  be  taken  that,  for  town  work,  with  the  car  in  good  new 
condition,  the  consumption  of  electrical  energy  is  at  the  rate 
of  95  watt-hours  per  ton-mile  taken  from  the  battery  in  the 
car.  If  the  road  surfaces  are  exceptionally  good  and  level, 
and  made  of  good  wood  paving  or  asphalt,  it  is  possible  to 
yse  solid  rubber  tires  instead  of  pneumatics  without  loss  of 
comfort,  and  at  the  same  time  to  obtain  a  slightly  diminished 


MOTORS  AND  MECHANISM  239 

consumption  of  energy,  say,  to  90  watt-hours  per  ton-mile. 
But  even  if  the  usual  route  avoids  all  important  gradients  the 
consumption  in  town  use  may  be  taken  as  100  watt-hours  per 
ton-mile  on  an  old  and  worn  vehicle. 

Weight — It  has  been  for  some  time  held  that  with  batter- 
ies of  the  type  now  in  general  use,  about  one-third  of  the 
total  weight  of  the  loaded  car  should  be  batteries,  the  weight 
of  battery  being  taken  complete — that  is,  including  all  liquid, 
boxes,  lugs  and  connections. 

Method  of  Transmission — Almost  all  possible  methods  of 
transmission  have  been  adopted  in  practice,  for  example:  (i) 
The  direct-coupled  motor,  in  which  the  motor  armature  actu- 
ally forms  one  piece  with  the  front  road  wheel.  Two  motors 
are  used,  and  the  armatures  are,  by  means  of  the  controller, 
grouped  in  series  or  in  parallel,  according  to  the  speed  or 
torque  required. 

(2)  The   single   reduction   geared   motor,f  in   which   two 
motors  are  used,  one  driving  each  front  or  each  back  wheel 
through  one  spur  wheel  and  pinion ;  or 

(3)  The  single  reduction  chain  drive,  in  which  one  motor 
is  used  to  drive  a  chain  which  passes  over  the  middle  ele- 
ment of  the  differential  gear. 

(4)  The  single  reduction  chain  drive,  in  which  one  motor 
is  used  with  the  armature  rotating  in  opposite  direction  to 
the  field.    The  armature  is  connected  by  a  chain  to  one  back 

i  road  wheel,  and  the  field  by  a  pinion  and  chain  to  the  other 
road  wheel,  thus  dispensing  with  the  differential. 

(5)  The  worm  wheel  drive,  by  which  a  single  motor  is 
placed  in  the  front  of  the  car,  and  drives  a  propeller  shaft 
connected  by  means  of  a  worm  wheel  to  the  middle  element 
of  the  differential  gear. 

A  feature  which  has  unexpectedly  turned  out  to  be  in  favor 
of  the  electric  automobile  is  its  limited  range  of  travel.  This 
has  the  effect  of  obliging  the  owner  to  keep  the  vehicle  in 
some  town  and  there  the  inducement  to  him  to  contract  for 
an  inclusive  annual  sum  for  the  maintenance  of  machinery, 
maintenance  and  painting  of  carriage  work,  maintenance  of 


240  MOTORS  AND  MECHANISM 

batteries,  supply  of  driver  and  of  a  substitute  car  in  case  of 
breakdown,  is  such  tl^at  this  plan  is  often  successfully 
adopted,  especially  in  Europe.  On  the  other  hand,  the  long 
range  of  distance  of  gasolene  or  steam  cars  and  the  danger 
of  their  being  subjected  to  rough  treatment  in  distant  places 
by  unskilled  attendants,  has  rendered  the  practical  develop- 
ment of  any  such  maintenance  system  in  their  case  almost 
out  of  the  question,  save  for  an  annual  sum  which  is  prac- 
tically prohibitive. 

This  does  not  indicate  that  the  gasolene  car  is  ^dearer  to 
run,  for  on  the  contrary  it  is  appreciably  cheaper ;  but  it  does 
mean  that  the  very  limitations  of  the  electrical  system  facili- 
tate supervision  and  the  formulation  of  maintenance  contracts 
which  many  owners  of  cars  prefer  owing  to  the  difficulty  of 
getting  good  drivers  and  the  advantage  of  having  a  stand-by 
car  in  an  emergency. 


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